7 1/4" Axle Education

Jim Kueneman said
Can some one make me smarter about these axles for my '63 Dart. If I go to Yukon they have gear sets for '66 and up axles. What is different about the early axles compared to after '66?

Thanks
Jim

i know early 7.25 have different backing plate bolt patterns than later housings also early gears can only be used with early cases on the 7.25.