I pulled this from a mustang forum:
You may need to change the pinion yoke because the stock Versailles yoke used a constant velocity joint.
* The 3" Versailles housing is super strong and has the larger axle bearings so keep it, but I would suggest you use different caliper/rotor setup becasue the Versailles setup is heavy, the caliper emergency brake actuation design was poor and can be troublesome, and parts are getting rare and more expensive. I'm about to make the swap myself but haven't decided what brake setup I'll use.
* As mentioned, the mounting flanges are about 1" narrower on each side than a stock Mustang rear end. I really like this becasue it allows me to run a 10" wide wheel and have only a little stick out beyond the fender lip - a look I really like. Just be sure to measure your backspacing carefully and get the right wheel you'll be set.
* Also as mentioned, you'll need to modify your spring plates to accommodate the 3" housing diameter. I slotted my plates long ago and never did like how it turned out. I'm about to either buy a aftermarket set or design and build my own.
* The Versailles caliper emergency brake will work but you'll need to relocate the cable mount from it's factory location. This is what I did, and my ebrake works well (when the Versailles caliper is adjusted correctly). You can avoid having to relocate the ebrake mount by switching to different caliper/rotor setup.