go to parts site, lookup part you need, and most sites list the year range forr that part. like this
http://www.partstrain.com/store/deta...ior&vdesc=true
Product Fit
Fits 1998 Chevrolet Lumina Base 6 Cyl 3.1L
1995-2001: Base; 6 Cyl 3.1L;
there may have been minor interior trim changes from year to year, but i think external body (base model) was the same parts from 95-01, i see 95-01 on many parts, then sometimes 96-98, and i think 98-01 on a few... all depends on what part it is.