Well, I got this wrapped up fairly easily. The nut takes a 1 1/2" socket. It is extremely tight, and will probably take more leverage than you can muster to crack it loose while laying on your back with the truck on the ground.
I worked around this quickly by using a large breaker bar with a long pipe slid over it. I put the pipe up against the passenger side rear leaf spring (to get the proper rotation direction) locked the front hubs in and inched the truck forward in low range 4WD. Easy as pie. Then I used a steering wheel puller to pull the pinion flange from the pinion and replaced the seal. While under there, I reached up and checked the plastic axle vent at the end of the hose. Sure enough, it was stuck and not venting. Cleaned and freed it up and reassembled everything. No more leaks. It was spraying so badly before that there was gear lube splattered all over the tailgate!
