It's interesting to compare the '77 and '88 models of these cars, same generation but the dash and controls had changed so much they more resemble the GM cars of the '90s at this time. This one does appear to be quite well maintained.
Perhaps but in looking at these models all the way through that run till the whale change the dash General shape was pretty much unchanged in looking at the glove box, and overall shell seemed kinda consistent.
There are not alot of exterior parts that swap between 77-79 & 80-90 versions of the B-bodies. You almost have to park them side by side to see the differences but they are pretty major. Many of the body sub stampings are the same though. And interior parts do interchange. They even lightened the frames on the later cars.