upgrade both shafts to DOM tubing with 1340 billet joints. Try to stay away from conversion ujoints if you can, 1350 on all four corners of the ujoint. Swap the rear end pinion joint for 1350 if you don't have one already, my 2007 GMT900 worktruck came from the factory with 10 bolt and 1350 joints through the whole shaft and rear end.