I have tried to get new REAR doors latches from my dealer for my 88 SSE and been told that they were not available anymore.
I questionned the dealer about 89 model and they were available but with different Part numbers.
GM Dealer could not tell if they were compatible to each other.

I have then decided to purchase 1 latch to see the difference and just find out that they are just fitting as good the 88 part number was fitting. (

I am sure that many other Parts unavailable for 88 are available for 89 under a different Part number.
"The Tin soldier inspection" of the 88 parts vs the 89 model replacement part might be a good solution to find acceptable and suitable option replacement for obsolete part
number replacement.
GM marketing trick probably.