Driveshaft in....and only leaks when the front ends up...yoke is smooth and even. Suspecting bad seal and asume it's an easy replacement with removal of the driveshaft?
Not too bad really. Pry the old one out and tap the new one in. It's nice to have a piece of PVC that fits around the seal to use as a driver. As long as it's not corroded in, it shouldn't take more than about an hour or so.
Jack the *** end up so you don't get a ATF shower.