Update: Looks like the differential isn’t doing very well.
During the Indy I had a lot of smoke before the transmission blew up. It turns out the freeze plug-style inspection cover had popped off and was allowing some fluid to drop onto the driveshaft. I also had both dust boots on the inner CV’s develop large rips. I think the 155 mph top speed had something to do with that.
Along with replacing the CV boots I pulled the diff apart to inspect it and saw some troubling wear on the gear teeth. Since there wasn’t a lot of filings in the fluid I think the problem is heat related and I’ve decided upon an upgrade to the Ford 8.8 differential (the $200 cost for ring gear replacement in the 8.8 vs the $650 for Mazda rind gears had a lot to do with the decision, as did the wide variety of available ratios for the Ford 8.8). I’ve located a low mileage 8.8 locally and I’ve purchased an 8.8 explorer mount kit from Ronin Speedworks (http://www.roninspeedworks.com/powertrain/) and I’m trying to line up a good cooling option for both the diff and transmission to increase the longevity of both parts.