On 4WD vehicles there’ll be a transfer case that has three shafts running in and out of it. One shaft comes from the transmission to drive the transfer case. Another shaft runs to the rear differential to drive the rear wheels, and yet another shaft runs to the front differential to drive the front wheels. Seepage on this transfer case isn’t of concern, but it suggests checking the fluid level is a good idea. The plug for checking fluid level is just below the “a” in the word “Transfer.” You can see that the rear seal associated with the U Joint isn’t seeping at all.