Well ive actually seen several roadster pickups made from 2dr and 4dr sedans and even (gasp) a five window. Sorry but ive got a glitch that wont let me post any pictures but if youll check out the viva las vegas, anti blessing and the shifters car shows you should see at least one pickup thats been made from a sedan.

Either way your straight axle should work since all Ford axles are within a few inches of eachother.