I have a very late '71 with the .846 final drive ratio. Top end leaves something to be desired. The unit needs rebuilding, Can something be done to swap to the .705 without during the rebuild or do I need to swap the entire unit?
Original Post
Probably the cheapest way to higher gearing for more comfortable cruising is to ship your ZF to RBT TRANS in the LA area. Lloyd will strip the box, check for any badly-worn parts and install a different ring & pinion gear set, brand-new. Or, if you wish, he can install a lower numerical 5th gear in your box, for much the same results. Trust me- his work is impeccable and you do NOT want to try this at home! He isn't cheap, though. For more info, see the ZF transaxle subject page on this website. Lloyd answers question like this every day, and you get straight info direct from the source.