Need some help. Noticed a very large puddle of transmission fluid under my car. It has the original engine, transmission and rear end. The puddle was rather large. The last time I drove it the transmission was fine. In looking under the car, it is leaking where the rear of the transmission meets the drive shaft. As I was looking at it, I could see the fluid dripping. Any advice/help would be appreciated. I assume it's tranny tail shaft seal, but I wanted to see what you guys think. What do you think it is? The puddle is large. Is this a fairly straightforward repair? Is it an expensive fix? Any help you can give would be greatly appreciated. Thanks!