[95/GT/5.0]

I'm from the old school and always ran 90w gear oil in my Borg/Warner and muncie 4 speed manual transmissions.I'm getting back into hot rodding again and find these new five speeds and six speeds are running ATF in them.I just put a Tremec 3550 in the ole 5.0 and was told to use a full synthetic,not a blend, and to make shure it has no friction modifiers,or something called synchro-mesh I believe GM sells it.Is this true and what do you run in your Tremec or T-5?Is there a trans fluid that would help make the trans a little more quiet?