The major difference between the 1957 Ford YBlock distributor and later distributors is in the advance mechanism. All 57 Ford YBlock distributors from 57 and up have both centrifugal and vacuum advance. As stated above, you don't want a 54, 55 or 56 Load-a-Matic distributor unless you have the matching carburetor. Even then, they didn't perform that well.
The 57 distributor uses a ball bearing mounted advance plate that is controlled by the vacumn advance canister. This is the plate where the points and condensor are mounted. I have one of these in my TBird. They work great as long as the advance plate is free and doesn't stick. Normally, when you find one of these, the ball bearings are frozen and NOS replacements are hard to find.
Later YBlock distributors use a two piece advance plate just like those found in small block and FE distributors. YBlock distributors are specific to YBLocks as the shaft is a different length and the gear is located differently. Be wary of rebuilt auto parts distributors as many are small block Ford distributors that have been modified. Search this forum and you will find pages of information on this topic.
I'm a shad tree mechanic and former drag racer that has been working on old Fords for over 50 years. I hope I got all this right. If not, there are experts here that can help you further.
