Will a 4.3L engine from 1994 Chevy fit 1998 GMC Jimmy?

It's *possible*, but not a guaranteed bolt-in swap. While both are GM vehicles and the 4.3L was a common engine, there are potential compatibility issues depending on the specific sub-models of the Chevy and GMC. Things to consider:

* Transmission: The transmission from the 1994 Chevy needs to be compatible with the 1998 GMC Jimmy's transmission mount points and other drivetrain components. This is a major hurdle.

* Engine Mounts: The engine mounts might be different. The 1998 Jimmy may require different engine mounts to properly support the 1994 4.3L engine.

* Wiring Harness and Computer: The engine's wiring harness and computer (PCM) may not be compatible with the 1998 Jimmy's system. This often requires significant rewiring or a swap of the PCM.

* Exhaust System: The exhaust system from the 1994 Chevy may not fit the 1998 GMC Jimmy.

* Accessories: The position and fitment of accessories like the alternator, power steering pump, and air conditioning compressor might be different.

In short, while the engine *might* physically fit, you'll likely need to do significant modifications and potentially fabricate custom parts to make it work reliably. It's not a simple swap. It's best to verify compatibility by comparing detailed engine and chassis specifications for both vehicles before proceeding. Checking online forums dedicated to GM trucks and SUVs can also provide valuable insight from those who've attempted similar swaps.