I just read a recommendation by the national T-Bird club's authenticity expert re: lube for standard transmissions. He claims additives in the modern/generally available API service GL-5 80/90 have the potential to corrode the brass syncros, and you should use GL-1 instead. Where would you go to buy GL-1, and wouldn't the other service improvements of modern GL-5 lube likely more than make up for any possible brass corrosion? (though I must admit, when my transmission had to be rebuilt, it was because the syncros had failed!)
Can anyone shed light on this issue?
P.S. He is also still recommending Rotella diesel oil for it's ZDDP content, which Ted claims may corrode your cam.

6 VOLTS/POS. GRD. NW INDIANA