Stupid engine question...

[JohnnyMac333]

I have an 80 C-10 with a chevy 350 that is NOT a 1980... I know it is a post 87 engine because it has centerline bolt valve covers. What are the distinguishing characteristics between 88-95 and the 96-99(?) engines? Is there a way to tell them apart without checking the engine numbers? Thanks yall.

[eventhorizon66]

If it has six intake manifold bolts per side with the middle two at a different angle, it has 87-95 heads.  If there are only four intake manifold bolts per side, it has L31 vortec heads.

[JohnnyMac333]

Ok, thanks. I was pretty sure that I had 87-95 heads, but then I read something that threw me through a loop. I didn't realize that Vortec heads came out in 96, I thought they came out in 99. SO I have spent the past two days trying to find information about an engine that came out after 95 but before Vortec. Unsuprisingly, my search has yeilded few results.... What a rookie hahaha. Thanks for the help.

[eventhorizon66]

87-95 = L03/L05 = Six bolts per side, middle two at a different angle

96-99 = L31 = Four manifold bolts perside

99-up = LR4/LM7/LQ9 = Gen 3 - A completely different animal, nothing in common with the previous two

During the overlap period of '99 the L31 engines were still used in the fullsize SUVs, which kept the previous year's body style, and the trucks got the new Gen 3 engines.

All "Vortec" means is GM truck engine.