[Humbucker]

New info...

I spoke with Tremec for about 30 minutes today. Interesting what the tech guy told me. He said Synchromesh was recommended only for sound dampning reasons. Apparently the 3550 started out as a truck transmission in it's past life and the cut of the gears make more "whirring" than others. The Synchromesh is a slightly thicker fluid that helps tone the noise down a bit.

He clarified the ATF may shift better, but the transmission noise will be greater. When I told him what kind of car I had, sidepipes and all, he seemed to agree that ATF would be a better choice for my application. He did, however, mention that they only recommend a couple brands, and that Redline and Royal Purple wasn't one of them. He mentioned Mobil 1 and another. I forget which, but he said it really didn't matter. In the end, he recommended I find out what was in there and put that back in.

Interesting...