i have a 1972 Ford f250 with a 390. I also have a 1986 ford f150 4x4. My question is, would it be possible to put my 390 in the f150? they have different engine, so what 4x4 transmission would bolt onto a 390?

 

You need a FE transmission. The old truck had a divorced transfer case. I believe the 86 is not. If the FE is good why not sell it and take the money to put towards the engine you need for the '86. If the whole truck is decent sell the entire truck.

On the flip side anything you can imagine is possible when it comes to automotive. All it takes is money. You might be able to find an adapter for the engine to your trans.

 

The reason i dont sell the engine is because i just bought the truck, both the engine and transmission were just rebuilt with a bunch of after market parts. Right now the truck has around 375HP, so i dont want to let the engine go.

 

It depends on what trans is in the 86. If it's a manual, then simply getting a bellhousing to fit the FE would mate the trans to the older engine. You'd be on your own about either modifying the FE bellhousing to accept the hydraulic clutch or converting to the 80-83 mechanical clutch linkage.
If you have an auto, then you would need a C6 to fit the FE, but I don't think there was ever an FE C6 made for a mated transfer case. A good trans shop could swap the tailshaft and make you a FE C6 to accept the TC, but it won't be cheap. The trans would have to be completely disassembled, along with another 4wd C6 to get the "donor" parts.

Other things to keep in mind, the 86 would most likely need a rear sump oil pan, and most FE's used a front sump. rear sump FE pans are available, but again not cheap in most cases.
Then there's motor mount issue to overcome. The FE went out of production after 76, so there are no factory towers for the 86 frame to fit an FE. Then, there's the radiator to think about. drastically different size between those 2 years, so you may need to get a custom radiator made to fit the size and locations of the FE water pump/thermostat housing.

It is doable, as others have transplanted an FE into later model trucks. Just not easily doable.

 

FE C-6's designed for a married TC are easy to find as they came married in F-100's with the NP-203's and 205's starting in 73, IIRC.

 

check the laws in your state...in some places, putting a older engine into a newer vehicle would be an automatic fail of the yearly state inspection (emissions, etc).