No need to check the data plates. If it is an '89 RS, it has 4.77s. I have never seen or heard of an '89 RS without 4.77s. It was the standard package when these vehicles were released here.
Now, if you can find out if these vehicles are actually RS Troopers, please PM me the locations if you don't mind. I have no interest in the 4.77s, but I really need a clean, damage free black dash panel. Worst case, if you wouldn't mind asking them for me over the phone, about the dashes, I would be mighty grateful.
Bart