kevlarsamurai

There are only three pro-Veteran outfits that really help us. The National Veterans Legal Services Program or NVLSP; the Veterans Pro Bono Consortium  and NOVA. They are there for us-for free.

NOVA = National Organization of Veterans Advocates. I belong as do most reputable VA Agents and attorneys. https://www.vetadvocates.org/cpages/home
It isn't cheap but it gives me everything I need for my CLEs and does research for us, too. 

By operation of law ( and Kuzma which superseded Karnas), you are entitled to the ratings criteria in effect at the time of your rating. If the laws change to a more beneficial interpretation, you are entitled to switch to the higher one. Conversely, if they become more restrictive, you are entitled to keep the more beneficial one. The VA can never come back and reduce you based on a changed regulation. 
The VASRD I attached was the original one from 1945. Nothing in it changed until after the Vietnam War was over in 1975. 
I'll ask NOVA if they have a better record of Part IV that shows the interim changes from '45 to now. Every time we discover a loophole, they slam it shut with a newer ratings criteria. 

It could mean other tests done by a private doctor-not sure at all 
There was a change in the ratings in 2006, that is included in this BVA decision:
https://www.va.gov/vetapp14/files3/1420703.txt
You might find somethig to help in the BVA search feature I just used:
https://www.index.va.gov/search/va/bva_search.jsp?QT=Pulmonary+function+tests+(PFT's)+&EW="alternative+criteria&AT=&ET=&RPP=10&DB=2018&DB=2017&DB=2016&DB=2015&DB=2014&DB=2013&DB=2012&DB=2011&DB=2010&DB=2009&DB=2008&DB=2007&DB=2006&DB=2005&DB=2004&DB=2003&DB=2002&DB=2001&DB=2000&DB=1999&DB=1998&DB=1997&DB=1996&DB=1995&DB=1994&DB=1993&DB=1992

Here's a copy of part 4 -the VASRD. It changed very little for most diagnostic codes over the years. I use it for my old CUEs because it shows the older ratings criteria. As Berta mentioned, if you really want to be sure, use the BVA decisions from the early years (1992-?). I look for appeals for increases where they will list the criteria then in effect for the evaluation of the different levels of entitlement.
 
1964 VASRD-Ratings.pdf

"  As we know, a CUE has to be worked with the evidence of the time and the law at the time... at least that is my interpretation" That is correct- but a CUE rests on established medical evidence that warrants a manifested outcome-
meaning the cued decision has to involve a rating of at least 10% in the decision being cued- or, that the medical evidence VA had  in their possession  at time of the alledged CUE warranted at least a 10% rating.
If there was no medical evidence to warrant a higher rating than "0" %, then there was no manifested detriment outcome to the claimant- because there was no $$$ compensation involved.
If the VA was in possession of medical evidence that would have established at least a 10% rating, but failed to consider it, that is a violation of 38 CFR 4.6, and a valid CUE claim. That is my favorite regulation, because VA over the past 2 decades has ignored my most probative evidence many times.
 
4.6  Evaluation of evidence.
 
            The element of the weight to be accorded the character of the veteran’s service is but one factor entering into the considerations of the rating boards in arriving at determinations of the evaluation of disability. Every element in any way affecting the probative value to be assigned to the evidence in each individual claim must be thoroughly and conscientiously studied by each member of the rating board in the light of the established policies of the Department of Veterans Affairs to the end that decisions will be equitable and just as contemplated by the requirements of the law. (38 CFR 4.6)
 
 
 
 

If you are remanded, I dont see how you can raise a CUE with the BVA at this point-unless they made a CUE in the remand...
This is the VA Schedule of ratings, the diagnostic codes etc are about half way down the scrollbar-
https://www.ecfr.gov/cgi-bin/text-idx?SID=d6ea1b96ab8aaf3a64646c8f1af44e72&mc=true&node=se38.1.4_1118&rgn=div8
. " My CUE was granted by the RO as service connected back to 1995." Good for you!
"  But they used the rating criteria (I think) in effect for 2018. " You can check the ratings for the Diagnostic code at the above link.
"In 1975, it looks like there was a change to the schedule of rating and another in 1996"
What Diagnostic code are you looking for, as to past changes?
The BVA might help- under their search feature:
https://www.index.va.gov/search/va/bva.jsp
It only goes back to 1994 but if you search there under 1994,1995,1996 under the disability and Diagnostic code you might find info to help.
For example this is a very old BVA decision-(some of them do involve claims further back than 1994)
The decision reflects the changes in the ratings for the disability this vet had:
" veteran's tinnitus is rated under Diagnostic Code 6260. The RO rated the disorder as noncompensably disabling effective from October 10, 1995, and as 10 percent disabling effective from April 26, 1999. During the pendency of this appeal, regulatory changes amended the portion of the VA Schedule for Rating Disabilities pertaining to the ears. This amendment was effective June 10, 1999. See 64 Fed. Reg. 25202 through 25210 (May 11, 1999). When a law or regulation changes after a claim has been submitted, but before the administrative or judicial appeal process had been concluded, the law most favorable to the plaintiff must be applied. See Karnas v. Derwinski, 1 Vet. App. 308 (1991).
https://www.va.gov/vetapp00/files4/0031024.txt
Have you told us in other posts what the disability is and what the diagnostic code is and was in the older decision?
To claim CUE you will need to have the date of the older deision and also the rating sheet they sent with the decision.
Also you could search at the BVA for Karnas v Derwinski under your disability- as there could be more there to help you.
 
 

By all means send the SSDI decision to the VA.  If you are awarded based on a service connected disability they are required to consider this information.