How much can our trannys take?

I have a 97 Chevrolet blazer ls 4.3L
Im currently swapping out the 4.3L engine and installing a 383 502 horsepower 439 Torque Engine. How much can our trannys actually withstand? and where can i get a manual tranny for a 97 blazer that will withstand 502 horses?

The torque convertor needs to be replaced. The 4L60E has a week sun shell and it will break at the neck and you loose a few gears. TCI makes parts to beef them up or you can buy a total unit done from them. Or go back to the 700R4 but vac shifted. Manual with a scatter shield is one way to go - I like autos but as you said have to beef them up first.

You won't want to bolt that motor up to your stock trans. Take muddogs advice and at the minimum beef up what you've got. If you don't care about overdrive, toss in a built TH350 and you'll be set for the life of the truck.

If going the manual route, it may be worthwhile checking boneyards for a six speed from a camaro or corvette.

ill probably go with this guys transmission http://cgi.ebay.com/ebaymotors/GM-700R4-GODFATHER-TRANSMISSION-Chevy-Truck_W0QQitemZ330017607966QQihZ014QQcategoryZ3372 7QQrdZ1QQcmdZViewItem good up to 700 horses plus this guy knows what hes doing