The rear end running gear, Diff, Shafts, Disks and Brakes are worth getting. I didn't use mine because I had to cut the drive shafts off and couldn't find new ones within my price range
, be aware that the 4x4 and 2WD components are not compatable, that is to say the 4x4 rear hubs will not fit the 2WD drive shafts and so on. I think the 4x4 brakes are bigger but can't be to sure. Have a look an eBay at the price of LSDs and bolt on drive shafts, worth getting even if you just sell them.