Jimbo,

Might depend on the year of the engines.

What is the year of the truck engine (or manifold)?
What is the year of the car engine (or manifold)?

People sometimes mix newer-style (1954 and newer) and older-style (1953 and older) manifolds with newer and older heads (as some have said on this site). You most likely should find out if the angle of the downward tube on the manifold matches (so the exhaust pipe will line up properly).

Tim