how much horsepower will these axles handle?? it has a built 4.3 with around 350 hp, just curious

depends on how you drive. You need to get 30 Splines for the front. Alloy USA 4340 Rear Axle Shafts for the rear. Then you can forget about it for awhile.

Driving style will have a lot to do with how much the axles can take. Less skinny pedal means more things will last longer. Be aware though, when the axles are the weak link, something else is.

here in michigan we don't have many rocks so it is a mud truck.. it gets beat on pretty hard

stock toyota SA is equivilant to a D44...but like anything it will break eventually.