For any of you other 7AT people out there looking at rear end stuff, I think I finally found the information on the real difference in the rear ends between 7AT and 6MT. This is all "what I think I know right now", it may change as I learn more (or worst case, it may change once I buy parts based on this and find out they don't work!)
Supposedly, the only difference is actually in the thickness of the ring gear itself and the mounting flange on the LSD carrier for that ring gear. Basically the 7AT's 3.357 ring gear is 10mm thicker than the 6MT's 3.692 ring gear, and the thus also the mounting flange for that ring gear is 10mm further to the inside on the 7AT's VLSD vs the 6MT's VLSD.
If this information is actually true, then if you're putting an LSD unit into a 7AT rear end and leaving the stock gears in place, you need 7AT-specific LSD unit that's 10mm shorter at the gear mounting flange. But if you're upgrading to 6MT-size gears anyways, you should be able to drop a 6MT-model LSD (wider) + 6MT gears into the 7AT pumpkin without issue.
Beyond that, it's a matter of figuring out which aftermarket and/or takeoff gear sets from various other Nissans are which thickness, but I think the general rule is that most are the same thickness as our 3.692 6MT rear gear, and the 10mm-thicker 7AT 3.357 is the "special case" (both for our car, and several other Nissan/Infiniti AT cars which have that exact same gear ratio).
Last edited by wstar; 03-20-2014 at 08:10 PM.
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