Drive shaft seal

[BigRiig]

During a short day ride this past weekend, I noticed a clicking sound coming from the right side of the bike. When I parked it in the garage, there was a leak coming from the drive shaft boot. Gear oil fo sure. I've been meaning to rebuild the differential since there is grease/oil flung on the rear wheel.

This new leak solidifies that I'm going to need to tackle this project before putting any more miles on the bike. I am wondering about a couple of items:

1. Could the clicking sound be the U-joint going out? Should I just replace it anyway?

2. Is there a parts list or kit for rebuild kit for the driveshaft/differential?