I think I missed a symptom with my original final drive.
Yesterday, I gave my GT a good detailing so the rear wheel was as clean as showroom. Today, I went out for a casual 150-mile day ride. When I returned home I was just putzin' around the garage, looking over the bike and what-not. To my amazement, my rear wheel is still spotless. This has to be the first time EVER that I've gone for a ride and returned home with a squeaky clean rear wheel. I think my original final drive was leaking fluid from Day One, and I just missed the signs. Perhaps I just chalked it up to road grime, or brake dust, or, or, or... They don't call me the 'Village Idiot' for nothin'!