So my 1999 s10 zr2 4x4 blew a rod and im no mechanic except on bikes which im just starting school for that but anyway a buddy of mine gave me his 96 gmc jimmy with a running motor but its still in the truck now i have a motor just sitting here but its older like an 88 from a full size pick up so the throttle body is difrent and so is the distributor but the jimmy has almost 300,000 miles on the motor and this other one has like 80,000 miles on it and there all the 4.3l so which one do u put in because im struggling with this truck its been sitting since oct and its getting colder and soon snow so we need my truck. Help plz

 

The 96 engine will work just fine in a 1999. Switch intake and exhaust manifolds and all other stuff from your 1999 onto the 1996 engine. You really want to replace intake gaskets anyways - use Felpro rubber/steel ones for certain. Some good threads on replacing intake gaskets on this forum - but never use abrasive disks or wire brushes or power tools to remove old gasket material.

The 88 engine will definitely not work in a 1999.

Replacing engines in 2nd generation 4x4 Blazers is definitely not the easiest thing to do (bellhousing bolts amongst other things). Find a place inside to work on it inside and better yet also get a truly experienced friend to help.

Ask if you have more questions.

 

I went as far as doing the timing chain with those gaskets as well went my engine went. I used an 03 engine from a zr2 with 280+. Had to swap the same stuff over as les mentioned, but everything worked out fine. The spider injector was crappy, but I didn't have money at the time for that, it came a little later.