i have a 69 camaro over 400hp what should i do to the rear diff so i dont twist anything? is there a way i can hook the diff to the frame? is there any bars or kits?

What rear end? 10 or 12 bolt? What ratio? Single or multi leaf? General condition of the body? How much over 400 HP? What tranny?
Jim

10 bolt 373, muti leaf, good, 420hp, 700r

I think a good set of track bars will probably help with spring wrap but I would be more worried about the stock 10 bolt and axles first. You won't twist anything unless you can hook it up really well and you will break the rear end before you twist anything. In the future you could look into subframe links but with 420 Hp you would have to work pretty hard to twist the body if that's what you are worried about.
Jim

thanks, who sells subframe links?

Jegs bolt-on subframe connectors ar fine if you don't want to weld them in place. I have them on my car now AND I can say they REALLY stiffened up my car when I do no more then jack it up from the sides behind or in front of its tires.

And to me, a good old set of old-fashioned "slapper-bars" are fine to stop axle hop!! And mine are home-made!!

Just be sure that the snubbers hit the bottom middle of the front spring eye is all and then tune/adjust each sides snubber until you get a straight launch!!

Mine have 1/2" bolts and lock nuts so do hit hard and noisey but are great, imho!!

pdq67