difference in cabs, 67 vs others

[matthufham]

i was talking to an old man today who used to work at a chevy dealership back in the day and he told me a 67 truck had a different curved rear, and 68-72 had a more square rear. he didnt describe what was more square (the roof, the cab corners...) but he claimed the doors and every other part would be interchangable.

his proof went like this. his brother had a 67 and the cab caught on fire. they replaced the cab with one from a 68 and it was "more square at the back"

i call bs on this but i never heard this before so i don't know what to think. i know the rear window could be a small rear one on the 67 but he said both cabs had the large rear window.