Which drive?
Assuming an Alpha One (or Gen II), then it's coming from the lip seal on the yoke, or the O ring that seals the seal carrier.
If you're doing the work yourself, then you'll need a couple of special tools. The cover nut spanner and a small scale (0 to 30 in-lb is best) torque indicator. It's not a particularly difficult job, but it does require you to be meticulous when setting up the rolling torque for the bearing pack. To have the job done professionally, look at a couple of hours at least.
It's also possible (likely) that the surface on the yoke is worn and for that you have 3 options. New yoke, set the seal 40 thou deeper in the carrier so it'll be riding on a new area of the yoke, or a speedi-sleeve. I have used all 3 methods, and all with the same result, the drive seals with no problem.
Without knowing any history it's difficult to know, but if the drive is getting on, it would be worth getting a seal kit and doing all the seals. As you have to pull the drive gear and bearing pack out to do the yoke seal, the rest (2 more seals in the bottom of the housing) are another 20 minutes or so.
I always do all seals when I have anything apart.
Chris.........
