It depends on what parts you are looking for. The bodies pretty much stayed the same from 1988 to 1999 with a few minor changes like headlights and grills, but you can still get a 99 grill to bolt on to your 89 truck. The fenders, doors, hood, bed, bumpers, etc all stayed the same. There were a few interior changes especially from the 1994 - 1995 but again if your up for the task a 1999 dash will bolt into your truck, but you better be on your game as far as wiring. If your talking motors, then 1987 to 1995 were TBI and the parts are somewhat interchangeable. Now there are some exceptions. As far as wheels the 5 lug pattern is the same from the 1970's up to 1999. Now the 4 wheel drives are 6 lug so you can't use them, but any 2WD fullsize truck wheel will bolt on. Also the Caprice's and Astro Vans had the same 5 lug pattern. Hope this helps.
2003 Chevrolet Tahoe 4X4 5.3
2002 Chevrolet 2500HD 4X4 8.1 - BlackBear Tuned