What other years of truck beds will interchange

As a direct bolt on 88-98 GMT400 trucks used the same beds. There were some wiring changes over the years but nothing major, mostly in the location of the harness mounts.
The hardest thing is usually getting the bolts out, If you are in a rust belt state I would suggest just torching them off and using new bolts. Usually much easier and faster.
While you have the bed off is a good time to look over all the fuel and brake lines as you have full access to them. Be careful removing the old bed, they are not really heavy but they are clumsy to handle.

https://www.2carpros.com/articles/jack-up-and-lift-your-car-safely