I broke a stock output shaft in my 727 this March at the launch after about 350 passes. It's behind a 505 and I think it's only about 550HP (2,980 lbs @130 mph running NHRA Super Street) with 14.5"x32" MT slicks. I launch at 5,400 and it flashes up to about 5,900 rpm. The rest of transmission has been great (it's a well built CRT).