Just bought a nice lil 1 owner gem. 1987 K5 350 with a 5.7l , 86,000 miles without rolling over I was told. I have 4 belts, can’t find out any part numbers for any except maybe the serpentine is correct. The other 3 are V belts, K5 is from Cali so it has an air pump…. I l believe that’s what one extra pulley does based on a diagram I found. Main issue is the ac pulley was squealing like a pig. Belt seemed loose with no room to tighten it. It measures about 52-53 inches. I guesstimate that’s a tad long. As I figure out if it has coolant in the ac, I’m trying to fix all the belts in one motion…. Or as lil as possible. I can’t find many YouTube vids so I look at square body issues but nothing has matched quite yet.

 

Welcome

When v-belts get worn they get narrower and sit down in the grooves further - therefore they seem longer. Also, previous owner could have installed too narrow of a v-belt, making belt seem too long. Your v-belts should all measure 0.44 inches across the outside width.

You can look up your belts in this link. Be sure to read fitment notes as this tells you with or without things like A/C or P/S.

https://parts.gmparts.com/search?cat...dyNumDoorsId=7

According to this, for your typical 1987 Blazer with A/C and P/S you need the following A/C part numbers. No apparent difference for California:
15395 (39.5 length)
15555 (55.5 length)
15330 (33.0 length)
5K435 (serpentine)