Guess that might be a good idea!!!
David recommended Valvoline 80/90 for gear
oil. He felt that
synthetic can be more prone to leak past seals but to determine is your car more street or track when determining your rear gear
oil.
The center 3/8 plug on the bottom is the drain and the offset plug is for the diff cooler with another one being on top of the diff. He said that the
oil level should be right below the fill hole and to ensure the threads are cleaned of any oil or sealent residue before re-installing the fill plug.
He mentioned while teflon tape can and will work, he prefers Permatex The Right Stuff when sealing the fill plug. He recommended to tighten it till the taper in the threads stops it then a slight snug to finish it off being careful to not over tighten it.
The TT is indeed a TrueTrac and doesn't require friction modifier to operate. He also stated these thing run hot as heck and to not get concerned over the heat they produce as it's the nature of the diffs.
I hope I covered everything.