Axles Differences
 

IWondering what the major differences are between late and early axles. Also is there a difference between 944 na and 951 axles? I know there are differences in the # of splines but wondering if there is any length or strength difference. I have about 6 axles and cv joints laying around that seem to be in good shape and would like to reuse stuff I have vs buying new ones. I've noticed one set is a little bit shorter than others. The jist of my question is are all axles interchangable?

Thanks
Brian

Early an late axels........ One is long, and the other is Super short

85.5 and up axles drive the speedo, where in the early 944, the speedo is driven off the left front wheel.