To be short ... 
Specialists were created in 1955 when only combat MOS were supposed to be NCOs. 
Specialist 9 and 8   eliminated 1968 
Specialist 7              eliminated in 1978 
Specialist 6 and 5   eliminated in 1985 
The report did not say why 7, 6, and 5 were discontinued. 
I see no need for the Specialist "rank" to continue, just make them Corporal. 
The NCO outranking all Specialists was only "in house" Army.  Interservice, ranking was by pay grade.  I remember the problem when I was in a tri-service unit, where the Corporal E4 outranked the SP6, but the SP6 outranked the Air Force Sgt E-5, and the AF E-5 outranked the Army Corporal E-4.   "Who's in charge here?" 
Several times at the MCRD graduation we heard that every Marine is basically a rifleman, and from what I have seen, that includes Women Marines.

Services other than the Army did not have an "inferior" classification.  Following this ranking logic, non combat personnel in the Medical, Legal and similar fields should not have been officers but part of an inferior "Pro Corps" not requiring salutes. Yes, Military Intelligence had SP6 at my MI unit at Fort Hood in 1966.  At Camp Drake, Japan, in 1969 we had a Sgt E-5 Medical Records Clerk.  The theory was he might have to transport personnel and thus needed to be an NCO.  I went from SP5 Broadcast MOS to SSG in 1967. 
Frank


This paragraph from WIKIPEDIA really sums it up. 
On 1 July 1955, four grades of specialist were established: specialist three (E-4), specialist two (E-5), specialist one (E-6), and master specialist (E-7). In 1958 the DOD added two additional pay grades to give enlisted soldiers more opportunities to progress to a full career with additional opportunities for promotion. Thus the recognition was changed to six specialist ranks, and the pay grade was tied into the rank designation: specialist four (E-4), specialist five (E-5), specialist six (E-6), specialist seven (E-7), specialist eight (E-8) and specialist nine (E-9).  CSM Daniel K. Elder goes on to explain, "In 1968 when the Army added the rank of command sergeant major, the specialist ranks at E-8 and E-9 were abolished", because they were notional rather than actual.  "In 1978 the specialist rank at E-7 was discontinued and in 1985, the specialist ranks at E-5 and E-6 were discontinued."

IF YOU WISH MORE HISTORY ... 

​These specialist ranks were created to reward personnel with higher degrees of experience and technical knowledge. Appointment to either specialist or non-commissioned officer status was determined by military occupational specialty.  Different military occupational specialties had various transition points, for example in the band career field (excluding special bands at D.C. and West Point) a bandsman could not achieve non-commissioned officer status until pay grade E-6 was attained. In some military occupational specialties, a soldier was appointed either a specialist or non-commissioned officer depending on which particular position or "slot" that he filled in his organization.  Cooks were specialists, while a mess steward held the rank of sergeant (E-5 through E-7). 
Specialist grades paralleled the corresponding grade of non-commissioned officer (E-4 through E-7) only in terms of pay.  The specialist grades, although they outranked the enlisted grades (E-1 to E-3), were outranked by all non-commissioned officers (E-4 to E-9) and lacked the authority conferred on them. This is the major differentiation between a specialist and a "hard striper". 
When the so-called "super grades" (E-8 and E-9) were introduced in 1958, the specialist grade titles were changed to Specialist Four through Specialist Seven; and the new grades Specialist Eight and Specialist Nine were added as well.

     From:  Dick Ellis

      Date:  November 4, 2014

Subject:  Specialists

I saw lots of them at Ft. Bragg in 1967 before shipping to AFVN.  Medical (especially radiation techs) and intelligence...which Bragg was full of with Green Beenie Hq. right around the corner.

Dickie..


AFVN Group Conversations

     From:  Frank Rogers

   Dated:  October 29, 2014
Subject:  Bottle Opener [and Specialists]
I just noticed the .50 CAL BOTTLE OPENER in the Medals of America catalogue for $16.95, so those who won one in the reunion drawing got a real bargain. 
I can only find Specialist and SP5,  no SP6 (or higher) as someone was asking. 
Frank

     From:  Frank Rogers    

      Date:  October 30, 2014

Subject:  Specialist Implementation

​Here are clippings I received from my brother who was in the Army at Kokura, Japan, when the Specialist system was implemented in 1955. Click on attachments 12, 13 & 14 in that order.   I love the last line about how this will increase efficiency and morale.  Sounds like a lot of top brass bull.

​Frank


     From:  Frank Rogers

      Date:  October 30, 2014

Subject:  Specialists

Jim, 
I can't find the mail I was writing, but the note says it will be sent the next time I send mail, although I had not finished it. 
I just spoke to my brother who said he was at HQ in Japan when the change came and the NCOs converted to Spec 4, 5 ,6, 7 were not happy at all.  He knew of one SP4 later promoted and it was to NCO.  He doesn't know what the MOSs were.  He wasn't in when the E-8,9 ranks came. 
Frank


     From:  Steve Ashley 

      Date:  October 28, 2014

Subject:  Specialists

​SP6 and SP7s were legal and some broadcast specialists during the 70s.  I am not sure what other MOS's carried that rank. 
Steve Ashley


Specialist Ranks in the Army

October and November 2014

Also See:  Group Conversation on Army Enlisted Ranks 

     From:  Frank Rogers

   Dated:  October 29, 2014
Subject:  Specialist - From Wikipedia

​[NB:  Sorry, I couldn't copy Frank's exact graphic but this is nearly the same thing.   Webmaster.]



     From:  j s jnstraveler

      Date:  November 4, 2014

Subject:  Specialists

In the Army Security Agency we had some Specialists above SP5 in specialized field such as decryption and interpreting.  Also, I believe there were specialists above SP5 in Finance and Accounting at the higher commands.  I was a SP5 but didn't want to hang around long enough to see if there was a SP6 in my future. Two years, 11 months and 4 days was enough (22 months overseas), although we did have some fun while doing a good job


     From:  Jim White

      Date:  October 29, 2014

Subject:  Specialists

I see that you are up  at "Oh God Awful" again.  So am I, because I am still in Kansas and it is now almost 0300.  Thanks for the additional info on Specialists.   Am sure you have already seen Frank Rogers' rather thorough comments and research on the topic. 
Jim


Only the lowest specialist grade survives today, as the higher grades were gradually phased out. Specialist 8 and Specialist 9, were eliminated in 1968.  Specialist 7 was abolished in 1978 and specialist 5 and Specialist 6 in 1985.  At that time, the rank of Specialist 4 simply became known as "Specialist," which is how it is referred to today.  While the official abbreviation was changed from "SP4" to "SPC" upon the elimination of the SP5 and SP6 ranks, the SIDPERS database was initially authorized to continue using SP4 until such time as the change could be made at little or no additional expense in conjunction with other system upgrades.  The continued use of SP4 on automatically produced documents (transfer orders, leave & earnings statements, unit manning reports, inter alia), hampered the adoption of the new abbreviation (and, to a lesser extent, the absence of "-4" in ​the non-abbreviated rank) 

     From:  Ron Turner

      Date:  October 28, 2014

Subject:  Specialists

Jim, et al,  There were a couple of ADP (Automatic Data Processing) fields around 1963-65 that had only SPs up to E7 authorized.  I believe several signal fields other than ADP were SPs only.  Additionally, a little used but authorized penalty under Art 15 was redesigatnion of a NCO to the same level Specialist; allegedly due to faulty leadership.  

Regards, Ron

     From:  Ron Turner

      Date:  October 28, 2014

Subject:  Specialists

Jim, et al,  There were a couple of ADP (Automatic Data Processing) fields around 1963-65 that had only SPs up to E7 authorized.  I believe several signal fields other than ADP were SPs only.   Additionally, a little used but authorized penalty under Art 15 was redesignation of a NCO to the same level Specialist; allegedly due to faulty leadership.  Regards,

Ron

​​

by individual soldiers who naturally viewed the computer produced documents as the final word on what the proper term was. While uncommon, SP4 is still used.  One reason for the stubborn continuance of the use of the "4" is that some soldiers see the SPC as looking too similar to SFC, sergeant first class, and the "4" differentiates it better.  Nevertheless, SPC is the Army's official abbreviation.  

Today, the rank of specialist is the typical rank to which privates first class are promoted after two years of service, although PFCs may be waivered into the rank of specialist after 18 months time in service and 6 months time in grade. It is granted far more often than corporal (E-4), which is now reserved for personnel who have either passed the leadership development course or have been assigned low-level supervisory (with two or more soldiers under direct command). 


     From:  Jim White

   Dated:  October 29, 2014
Subject:  Specialists
From a web search, the SP7 rank was discontinued in 1968 and the SP5 and SP6 ranks were discontinued in 1985.  I could not find anything definitive regarding what fields were promoted to SP6 and SP7. 
If my memory serves me right, there were also SP6's and SP7's in the dental/medical fields, the musical field (bandsmen), and in some military intelligence fields (translating/interpreting, etc.).  I think Steve is right when he says they were also in the legal and some broadcast fields.  But, like Steve, I don't remember any others.  However, as a new twist, one of the clerks working at the motel where I am currently staying in Hutchinson, KS is a retired female SP6 auto mechanic.  So, who knows what others specialist fields might have existed.... 
Jim


     From:  Jim White

      Date:  October 29, 2014

Subject:  Specialists

Frank, 
Thanks for your well-researched comments on the specialist ranks.   I was unilaterally changed from a one-rocker E5 SGT to a SP2 E5 in June 1955 (at the time I was a personnel clerk).   Then in January 1958, I was promoted frm SP2, E5 to SFC (two-rocker) E-6.  WOW!  I had suddenly jumped over CPL E4 and SSGT E5.  This was just before the "super dooper" Super Grades came into effect the end of March or the 1st of April 1958.  From April 1958 to March 1959 I was at the Language School in Monterey, from April 1959 to June 1960 I was with the 528th Military Intelligence Company in Korea and from June 1960 to August 1965 I was with Headquarters, US Forces Japan.  I really don't recall seeing any Sp6/7/8/9, or for that matter, many MSG E8 or SGM E9,  during that period.  However, in September 1959 I did travel by troopship (USS General Mann) from Yokohama to Inchon while on my way back to Korea from R&R.  We had a number of "newly-minuted MSG E8s and SGM E9s" on board and "Boy, weren't they ever a bunch of stuck-up SOB's."  After all, they were in the officer and/or dependent class staterooms while us peons were down below rowing the boat. 
I agree that the present "SPC" system is rather foolish and the Army should go back to CPL for all E4s. 
Your quotes also note that the Navy had a "specialist" classification during World War Two.  The Army had a similar system with it's Technician Third, Fourth and Fifth grades (pay grades equal to Staff Sergeant, Sergeant and Corporal).   Click here. This article says that the Technician grades were eliminated in 1948 but I think I recall seeing some men wearing the "T" as late as mid-1951 when I went into the US Army Reserves.  And, I know that the saying "No one can f---k up more than a T5" was still around at that time. 
Jim


     From:  Steve Ashley

   Dated:  October 29, 2014
Subject:  Bottle Opener [and Specialists]
SP6 and SP7s were legal and some broadcast specialists during the 70s.  I am not sure what other MOS's carried that rank. 
Steve Ashley


     From:  Frank Rogers

      Date:  October 30, 2014

Subject:  Specialists

Hello Jim, 
Yep, if you watch some old movies you might hear the expression about  "- - - - like a T5", but the movie code back then did not allow your more graphic description. 
When I went into the Army in 1960, a lot of the initial turmoil was over.  I'll have to query my brother who was in the Army from 54 to 57, part of it at the Screaming Eagles and in Japan.  One man at Ft Eustis 1961 was an E-5 with rocker, and he was in Personnel.  I was Corporal there because the AF guy at induction center made a mistake, so I was Corporal until I passed pro pay test and had to "convert" to SP to keep my Broadcast MOS ... unless I wanted to become a Transportation NCO.  The Army almost put me in river boats, so, I could have gone to Vietnam and been long dead. 
I was at 500 MI at Ft Hood as SP5 and we had SP6, but can't remember any SP7.  Do you remember the "concern" when an MI guy showed up at AFVN HQ asking for me?   He was a former colleague at Ft Hood. 
Frank....


     From:  Jim White

      Date:  October 28, 2014

Subject:  Specialists

​From a web search, the SP7 rank was discontinued in 1968 and the SP5 and SP6 ranks were discontinued in 1985.  I could not find anything definitive regarding what fields were promoted to SP6 and SP7. 
If my memory serves me right, there were also SP6's and SP7's in the dental/medical fields, the musical field (bandsmen), and in some military intelligence fields (translating/interpreting, etc.).  I think Steve is right when he says they were also in the legal and some broadcast fields.  But, like Steve, I don't remember any others.  However, as a new twist, one of the clerks working at the motel where I am currently staying in Hutchinson, KS is a retired female SP6 auto mechanic.  So, who knows what others specialist fields might have existed.... 
Jim

​​

The Medal of Honor was awarded to SP4 Michael J. Fitzmaurice by President Richard Nixon at the White House, October 15, 1973