78 crew cab owners need measurement

[RootBreaker]

ok so i someday want to drop a crew cab on my frame... dont want the longer truck for offroading..

i know the frame has the bends and sort... i would need the crew cab and the cross member..

does anyone have a crew cab without a cab that they can measure back how far the cab mounts are apart from each other?
just some future looking... and yeah i may by a long shot have a crew cab.. most likely not but u never know...