I do balance work my self,I have SW engine balancer still in my home garage now that I'm retired and closed down my shop 10 years ago.,and do race car engines still for old freinds. Here is the facts on short drive shafts/they must be lined up on the money and put together strait,of all the short shafts I've done over the years,I've yet to find one out of balance I did,even though I check them. Yes I have had to fix a few that came to me some one other then me did,,taking them back a part some times. Race car shafts often run some very high RPMs cuz of rear high # gears