'78 305 into a 92 gmc?

[jpjohnson]

Anybody have any experience putting an early model 305 into late model pickup?

[Blazin]

If your running manifolds you could possible have issues with the dipstick clearing them. Heater hose routing is different. If you want to run the 92 fuel system you will need to use the heads from the newer motor. Injection intake wont bolt to the early motor. Flywheel / flex plates don't interchange either.

[frotosride]

If you have an automatic tranny you will need to find a throttle position sensor that will allow the tranny to know when to go into gear. this was fun on a '91 blazer 383 swap...also remember that the efi pump has way to high pressure to use a carb on. easy and reliable solution is keep the pump and return line, and run a regulator at appropriate psi for your carb with oe return line bleeding residual pressure from th regulator.

[kmcbride74]

I'll bite and ask the obvious...Why would you want to do that?

[slammed79]

Just to toss it out there, if a half smart emmissions tech notices the difference in the heads on a visual inspection, you may run into issues. Most states that have emmissions will let you swap newer into older, not the other way around.