My front crossmember, under the engine, is rusted at the bottom from water laying in it. I found a nice front end section from a 40 Buick. (It was cut out to make a hot rod with Mustang II) Anyway, both being GM, are these two frames the same? I would like to replace just the crossmember. The A arms measure the same. Did not know if someone had an interchange book that may cover this. Thank you. New to the club.
When comparing different GM makes it is likely/possible that numbers change by division for the same part. Here are the numbers,but careful comparing of the parts is the best bet.
LaSalle 1939 1434365
1940 1438142
Cadillac 61 1939 1434364
Buick 40-50 1940 1394831
60 1940 1394830
80 1940 1394905
Warren
While bodies were shared between Buick and LaSalle I'm not sure the chassis were. Very different engines/shapes may have necessitated differences in the frame. It's a good question but I'm not sure can be answered from the info that exists today. I think Warren is spot on and it will require you to put each piece side by side, take measurements and compare them.
Just find a good hot rod shop in your area and have the 'man' take a look. Any good fabricator can slice and dice your new cross-member to fit your car. In fact, your current cross member can probably be repaired a lot easier than cutting it out and replacing it. It is made of Oh-very-thick-stuff and lends itself to a patch to replace the rust. The you don't have to worry about replacement and the patch will be as good as the original.