OK, so i am in the middle of doing and engine swap in a 1990 4x4 f250 lariat. We bought a 1994 f250 for its 351w(the same engine in the 19909 f250).Now if i understand, i should just have to put the distributor
from the 1990 on the 94 engine and it should bolt right up in. PLease correct me if im wrong.

 

are you just using the block and heads? some of the accessories are different. alternator, smog lines, some wiring. just use EVERYTHING from your old engine and nothing except maybe the injectors from the new engine. the 94 injectors are 4 hole ev6 i believe, and your 1990 injectors are pintle style. Im swapping a 1988 5.8 into my 1994 5.0 truck right now.

 

You can't use any wiring from the '94 and you can use the '90 distributor but you first have to put the steel drive gear from the '94 dizzy on it, the newer motor has a steel roller cam in it so it needs a steel distributor gear or it will strip and fail in short order and seize the motor.