I don't know if Cad went to the higher flywheel teeth count in 54 like Olds did. If it was Olds, then it would mesh. The 2 Olds starters would have the same amount of teeth on the starter, but they are not the same diameter. There must be a Caddy guru here that knows..bumping this to the top.
my USA parts supply catalog lists a 50-52 53 54 55 56-60 61-64 so... looooooks like it's a single year type thing, but I'm not 100%
Thanks for the info guys. Unfortunately I don't have a starter at all, so I don't have anything to compare. I just found a guy here on the hamb that has a '56 starter for sale.
well, depending where you're at... here's a salvage yard between Olympia, WA and Portland... wouldn't hurt to give em a call http://www.cadillacville.com/