Does anyone know what vehicles had the easiest 9" rears to swap into a 92 rs? Also would a 9 hold well under 550hp?

 

No such thing as a 9" that will swap in from any other car. It's a Ford rear, so all the Ford brackets would have to be cut off, and Camaro brackets welded on. Preferrably on a jig so everythings in perfect alignment. May need to narrow it too and get custom axles.

Not sure what you'd do for the torque arm...

Better off just buying a bolt in kit from Strange, Currie or Moser. They say mine will hold in excess of 600 HP and TQ. Good enough for me.

 

Moving all the brackets over to a junkyard 9" isn't hard. The hard part is finding a way to economically attach the torque arm.

Third gen diffs are actually narrow compared to most junkyard 9" diffs. I use a housing from a 1970 F100. I use ladder bars so I didn't have to worry about mounting a torque arm.

Strength of the 9" depends. The weaker ones onle have 28 spline axles but even a factory axle is stronger than anything available for the 10 bolt. Ford also produced 31 spline axles 9" diffs. With little to no modifications, a factory 31 spline 9" could easily handle 600+ hp although I'd get aftermarket axles at that point.

Like any other diff, there's always room for improvement even on a 9". Your best bet is to bite the bullet and buy an aftermarket bolt in diff. You can cut costs buy buying a housing package. It inclused the housing that's a direct bolt in plus axles. You then buy a center section with whatever posi and gears you want. These can be picked up locally for a lot less than buying them in a complete package deal. The housing package is around $1000 while a complete diff is closer to $2400 now depending on what internal parts you want.

 

how much will the 28 spline hold? I can get an old used rear real cheap, also know a few good machinists thatll narrow it for me too. Welding the brackets isnt going to bother me. thanks for the help guys.