49 to 52 Chrysler and DeSoto used substantially the same body. The glass will interchange. So will a lot of other parts.
Biggest difference? The 49/50 front end was restyled for the 51/52 model.
So were the rear fenders.
I also have a sneaking suspicion the doors will interchange between Chrysler/DeSoto/Dodge and Plymouth but have no proof of this. Just that in pictures all 4 cars look an awful lot alike. Except the DeSoto/Chrysler body looks about 4 inches wider.
Other than the front end (forward of the windshield) and the rear fenders practically everything will interchange, both mechanical parts and body parts.
The Dodge/DeSoto/Chrysler body is longer and wider than the Plymouth. Nothing on the Plymouth will fit the D/S/C body, or vice versa.
The side glass will interchange 1949 through 1952, but windshields are 1949-50 and 1951-52. The latter glass is wider than the former - note the narrower A pillar on the 1951-52 models as compared with the 1949-50.
There are three sizes of rear windows - 1949, 1950 and 1951-52. Dodge/DeSoto rear windows are the same as above, but the 1951-52 Chryslers used a 3-piece rear window with wrap-around glass.
Rear doors will interchange for all years, but front doors are 1949-50 and 1951-52. The front fender line was raised for 1951 decreasing the distance from the top of the fender to the top of the hood. If you follow the fender line on the 1949-50 models into the front door you land up just below the door's key lock. On the 1951-52 models, you land up just below the door handle.
Rear fenders on DeSoto and Chrysler are 1949, 1950-51 and 1952. Both DeSoto and Chrysler had the taillamps increased in size (height) for 1952. Dodge rear fenders are 1949 and 1950-52. Trunk lids apparently will fit 1949 through 1952, but the 1949 models had the trunk-mounted brake light. Thus 1950 through 1952 trunk lids are virtually identical.
The Dodge front clip is 2" shorter than the DeSoto/Chrysler Royal/Windsor. That is how the 123.5" Dodge wheelbase was increased to the DeSoto/Chrysler's 125.5". The straight eight Chryslers were built on a 131.5" wheelbase, again all in the hood. The 1951-52 New Yorker and Imperial continued with the longer front end while the Saratoga shared the Windsor nose.
The Plymouth wheelbase was 118.5" - and the 5" difference between it and the Dodge was all in the passenger compartment. Thus the doors of the Plymouth are shorter than the D/S/C doors. And as the Plymouth was narrower than the D/S/C models, the windshield and rear glass is smaller, as well. Plymouths may look like their bigger brothers, but that is as far as it goes.
Bill
Vancouver, BC