rating on differential

[87RX7RACER]

From what I understand, if the RX7 diff is the same as a 1.8 diff as far as ring gear goes, then here is what it's good for:

On slicks the factory RX7 diff with upgraded mounts will do about 350 whp for a while with a manual transmission as long as you don't do crazy 5,000+ RPM launches all the time. An automatic will do about 400 with a good converter.

[zukitek]

The nissan R200 diff will handle most anything you can throw at it but you will want the HLSD from an S15.
There are R200 diffs all over pullapart in J30s,Q45s, 240s ,300zs,pretty mcuh anything rear wheel drive with IRS for probably around 75-100 bucks and you can buy an OBX (quaiffe knockoff) LSD for 375 on ebay. The catch to all of the alternatives is having to mount the diff without the use of the powerplant frame I guess.