I have a 64 F100 with a 390. The truck originally had a straight 6. Someone modified the truck with a welded in cross member, looks like a T-bird member, thats in the shape of a tube. Will 65-72 headers work for me. Thanks.

 

That will probably be the safest route to go. Becasue the 65 came with the FE series motor available, they should work in your 64.

--Mike

 

The 65 headers will not fit if it has a manual trans. The header will hit the clutch bell crank .
Monte