The pre-80 First gen RX7s do not have LSDs in them. The 81 and up of the same body style does, and they have disc brakes. But, they have that oddball 4 on 110 bolt pattern, with only 2 or 3 custom wheels available to it.
i think its a 76 style RX7 GSL-SE has the LSD rear end. or so i hear. its got disc brakes and also a watts link/mounts setup along with it which you'll have to cut off. also i heard on some forum that you can just swap in the 3rd member from taht rear end into the mazda rear. but no matter waht you have to get the yokes changed on the driveshaft to make it work right and redrill the bolt pattern to 6 or 5 lug unless you wanan be stuck with the 4 lugs. they look very very similar to the mazda pick up rear ends.. let me know how it works out.
RX7s werent made until 1979. And liek I said before, it was the 81 and up that had the LSD and disc brakes. I know, we just did a rear end swap in my friends 79.
I am gonna use a pathfinder rear end it has LSD and discs and from backing plate to backing plate they are pretty close to the same size!!. I am gonna have to take the wheels off and mesure from their mounting surface just to make sure
Not all RX-7's from 81-85 will have disk brakes and LSD, only the GSL or GSL-SE that I mentioned. If it has disks, it would have had factory LSD, but drum/open rear end cars out number GSL or GSL-SE cars by at least 10:1.