[shifty]

Looks like a 2000 OBS, but anyone else feel free to correct me if I'm wrong. If I recall correctly, they continued the OBS longer on the C2500-C3500 longer than the C1500.

If it's the case, I think you'd want to stick with parts from late 90's GMT400 platform. But what I usually do is inspect the part, find the part number, then go to a parts site like GMPartsGiant or GMPartsDirect and plug the number in, go to that part's page, then look at the compatible vehicles list. This isn't *always* 100% correct, but the only time I can recall it failed me during many dozens of JY runs with a door buzzer module of all things. With "normal" mechanical wear-and-tear parts, it's always hit a homerun.