Guess Wat... I finally found it, just havent found the picture of the blown diff...still working on that one. after looking in rx7city, teamfc3s, nopiston, slcrotary, fc3s.org, and other smaller forums, I remembered it was in a V8 conversion topic...

FROM granny's General Info"...The stock RX-7 rear axles are amazingly durable (internally, the parts are similar in size and even stronger than the Chevy 10 bolt that comes in the newer Z-28). While we offer bolt-in narrowed rear housings and axles for the 1st gen. cars, unless you are REALLY going to abuse it, we suggest you try the stock rear first. There are many V-8 powered 2nd gen RX-7s on slicks running mid-10 sec 1/4 mi times on the stock rear, a feat that requires 475-500hp. The clutch type limited slip up thru '88 is very strong 4 pinion style much like the diff design used in the Dana 60. Although it may be hard to believe, the rotary powered RX-7 drag racers are probably harder on the rear than the V-8 powered guys. The reasoning behind this is that most all rotary powered RX-7 drag racers use a manual transmission, a metallic clutch, and a heavy flywheel spinning at 9-10K rpm to assist the low torque rotary in launching the car. An incredible amount of stored energy is released into the rotary drivetrain to launch the car, enough to launch the car well even if the rotary engine died on the line. In the case of the V-8, plenty of torque is on tap to allow low rpm starts, also making it much easier to modulate the power to make the most of available traction."

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