i went to buy a new brake cable as mine broke, and they gave me 3 different sizes. anyone know how long the intermediate brake cable would is on a 1994 f-150xl 4.9l v6 5 speed standard 4x4 regular cab.

 

With your front wheels straight ahead, measure from the center of a rear wheel hub to the center of the front hub on the sane side. That measurement is your wheelbase. Tell the guy at the parts store what your wheelbase is and he should be able to give you the correct cable.
Alternatively go to rockauto.com and enter your truck details and see what they list for your wheelbase.
Minor detail but you do not have a V6 but a straight six.