1932 to 1952 were pretty similar. I think some where they raised the compression a little, but parts interchange. 1953 was a one year deal with a relatively flat piston and the much smaller combustion chamber. Octane numbers increased a lot during the 1950's and early 1960's. A lot of aftermarket pistons were offered with pistons to raise compression ratio. A lot of engines that are being disassembled these days have aftermarket high compression pistons that were aftermarket and manufactured by companies that no longer exist. A lot of them were sold under the Burd trademark by Washawsky Bros/JC Whitney.
