84 720 Bed swap questions

Ive got an 84 xcab 720 which has the bed lip on it. I want to swap on the 85/86 bed to change it up a bit, but in some preliminary measuring, I noticed that the newer bed is "smaller" at the top than the older. my bed lip stule bed is 76x60. the newer style is 75x58.5. did they change the rear of the cab profile on the last two years of this truck? or did the bed just shrink a bit in the design change and it still matches up to the 84 cab fine? any know for sure? if i didnt have to modify the bed to get it over my notch I would just swap it on and find out.

im not sure what year the bed is that we got for a buddys build but were doing the same thing but when i measure the width at the bodylines i get the same measurements on the cab and bed so im not sure what your experienceing

the cab did not change profile. people swap the beds all the time.

im not measuring the bodylines, im measuring the top of the bed. this all started because I want a canopy. Im just going to take jeffs word for it and start cutting on the newer bed
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There is a difference between standered cab beds and king cab beds whith the wheel wells but you can still use it. other than that you'll b fine.