Do you know how much HP and torque a M-21 can withstand? Looking at putting in a 505 big block?

 

id say about 600-700 all around.they put them behindthe zl1,and that had about 550.ive got about 600 on the motor and mines been fine.im affraid to spray it tho'!i guess traction would have alot to do with how long it will last.

 

Do you know of a good place to buy a rebuild kit for a m-21? My third gear is going out.