I think most started breaking around 400 miles. I think the majority of the failures have been on 163's too! A few 154's, I don't know about 146's
First post here but, Was riding sicamous last week and my driveshaft spun at 485 miles just ripping around in meadows about 3' deep. I talked to the dealer there he said he was 2 week behind so they couldn't help but did say they are adding a sleeve to the shaft long enough to butt up against the ribs in the center and then welding it all the way around with good results. Im waiting for the word from my dealer in calgary they said the new shafts are to be in this comming week they didn't know if the new one's are beefed up or not. I guess we will see. BTW im ridding a 154 everest.