The number on the starter will tell you if it's for a standard or Hydra (Hydramatic, derived from 'hydraulic' and 'automatic'). They are also different between the '51/'52 and '53 - '55 models. Here are the numbers:
1107087 was used in 1951/51 Standard trans
1107088 was used in 1951/52 Hydramatic
1107125 was used in 1953-55 Standard trans
1107126 was used in 1953-55 Hydramatic
These are all Delco-Remy numbers. Earlier KF products used Autolite. The numbers on the tags may be hard to read so look carefully.
If the number is there and legible, you should be able to tell what it fits.
