Does a s10 1996 4.3 engine fit in 1998 s10?

Yes, a 1996 S10 4.3L engine should fit in a 1998 S10, but there might be some minor differences to consider. The engine itself is largely the same across those years, but you might encounter slight variations in:

* Wiring harness: The wiring harness connectors might be slightly different, requiring some modification or adaptation.

* Computer/ECM: You might need to use the ECM from the 1998 S10 to ensure proper operation with the vehicle's systems. Using the 1996 ECM *might* work, but it's not guaranteed.

* Sensors: Some sensors might have different connectors or specifications, though this is less likely to be a major issue.

Essentially, while the engine *physically* fits, you'll likely need to address some electrical compatibility issues. It's not a simple drop-in swap. You'll probably need some mechanical and electrical knowledge or the assistance of a mechanic experienced with these trucks.