The transmission case is plenty full... in fact it's the only part that seems to be retaining its oil. Using 85 or 90 weight ln there.
I don't think I have ever heard of BG Gear Lube, but I'll check it out. Every type of grease I've used in the gear box has gotten squished out the lower end by the gearshifting action, but the black stuff has proven to be less prone to excessive leakage. Will the BG stuff stay in there?