Tom, I have pulled the pinion yokes a couple of times. Probably on the output shaft yoke the challenge will also be breaking the nut loose from the shaft, and pulling the yoke off the shaft. You'll need a good impact, or long cheater bar, of course. I had to make a 'puller' to pull the flange, a thick steel plate (3/8" I think will fit between the oil slinger/protective flange and yoke) with a U groove to fit down behind the yoke and a bolt hole in each of 4 corners, four threaded rods to cover the length of a hydraulic jack, and another plate at the base of the jack. Said jack laid on it's side of course to push on the end of the pinion. The yoke was really on there. The whole truck seemed to jump and the jack and puller became airborne when it came off, so beware.
I can look up the lube seal number if you want to replace it (the reason I pulled mine). The original was a two piece seal, replaced by a one piece seal. There's a thread on it. [edit, on second thought the transfer output seal might not be the same as the differential pinion seal that I replaced] YMMV