I’ll bet the gears moved slightly and the forks are not engaging properly when you’re installing the cover. The “hump” on the first/reverse fork must be at the rear of the transmission and the other one with the slot must slip over the ring on the synchronizer drum. Slide the gears back and forth and find the center of travel and then the cover should go on correctly. Here’s that page in the manual:


http://chevy.tocmp.com/shop/1948_51truck/51ctsm0704.htm


1952 1300 Canadian 1/2 ton restomod
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