I have a 1997 f-150 w/4.2 that is bad and needs replaced- can I drop a 1999 4.2 in without any problems ? If not what may I encounter ?

 

I beleve the basic block and heads are the same. Are you just going to replace the long block or were you thinking of swapping complete including manifolds and electronics.

 

JUST TRYING TO MINAMIZE THE WORK WILL USE WHATEVER I can from 99 without changing anything that dont need changed

 

I think in 99 the 4.2 went to fail safe cooling. If so you will have a cylinder head temp sensor on the 99 that was not on the 97. The 97 will have a coolant temp sensor and the 99 will not. You might have to swap a few parts around. Have a close look at the cylinder head and compaire it to yours.

Regards

Jean Marc Chartier