Ouch!!!
99pinger, is correct grade 8's are the sh*t. Used for hitches, framne mounting, anything with wicked shear force.
BUT, stainless ain't no sissy metal. If you sheared stainless AND it didn't fubar whatever it was holding, stay with the stainless. The grade 8 will cut through the mild steel. At a certain point, breakage is good. Grade 8 if/when it breaks it's always a bad thing.
BTW, you hit a tree hard enough to trash the the stock bumper, your lucky to still have teeth. When I was first learning about these little Blasters (at my friends Blaster's expense!!) I was trying to see how big of a tree I could I could hit and bend over. 2" was about it for those that want to know. Anyway, I had a couple that bent just enough to send the dam thing up and back at me, but when I hit one that didn't care about a few hundred pounds of BVlaster and my ass, it was a nasty stop.
Why?
There is alot of aluminum in the motor, the A-arms have play, steering is multi part and the frame is a left and right with spars. A good hard nasty smack can change alot of stuff.
Pay attention to how things go back together. If it don't line up there may be reason. The last thing you want is a crck in the frame and have it fail in the middle of a jump. Be climbing a wicked hill and the motor comes loose or you lose a wheel or one wheel goes all by it's onesy...
Anyway, be careful and know your machine.
A