Challenges and Considerations:
* Engine Mounts: The engine mounts will likely be different. You'll need to either fabricate new mounts or adapt existing ones.
* Transmission: The transmission compatibility depends on the specific transmissions in both vehicles. You might need an adapter or a complete transmission swap. This is a major undertaking.
* Wiring Harness: The 1996 Vortec's wiring harness is different from the 1990 Sierra's. You'll need to either modify the existing harness extensively, use a stand-alone engine management system (like Megasquirt), or find a harness designed for the swap. This is often the most complex part.
* Computer/ECU: The 1996 Vortec ECU won't work directly with your 1990 truck's system. Again, a stand-alone system or significant rewiring is required.
* Exhaust: The exhaust system will need to be modified or replaced to fit the Vortec 350.
* Cooling System: The cooling system may need modification to ensure proper fit and function.
The Cam:
The camshaft in a 1996 Vortec 350 is *not* a "RV cam." Vortec 350s were known for their relatively broad torque curve, making them suitable for towing and general use, but they were not specifically designed for the low RPM, high torque characteristics of a dedicated RV cam. A dedicated RV cam would likely be even less aggressive. The Vortec 350's cam is a good compromise for performance and driveability.
In short: While the swap is *possible*, it's a complex project requiring significant mechanical skills, tools, and potentially a fair bit of fabrication. It's not a weekend job. If you're not experienced with engine swaps and automotive electrical systems, it's best to seek the help of a professional mechanic. The cost of parts and labor could easily exceed the value of the truck if you aren't careful in your planning and execution.
