Ok so I have what I believe is a vin w vortex v6 4.3, but I also have an engine out of a Chevy Astro that has a different intake manifold on it. I want to take the intake off of the blazer and put it on top of the Astro’s engine since the blazer’s motor is bad. So are there any differences between the two engines? The blazer has cpi and the Astro is something else or carb I think.
Welcome to the site.
GM used V6 4.3 CPI until '95 in Blazer and Jimmy. In '96, MPFI was installed. Head castings may be the same. I've never looked them up. Emission stuff changed between the two years. Vans used TBI up to until the switch in '96.
Ask the performance section. The engine guys know differences better than me. I'll look through my information for differences. The switch also happened to V8 models. TBI to MPFI.
'83 Silverardo XST - ZZ4 powered
'95 Jimmy SLT (Bought @131,814)
'96 GMC Jimmy LS Ret. @236651 miles
'08 GMC Acadia 3.6L SLE
Gain extra benefits by becoming a Supporting Member 
