I am trying to replace the pinion seal on my 1993 2500 HD. I am using a
1 1/2" 12 point socket and a 3/4" drive 2' long ratchet. For the life of me I can nut budge that nut. Is it a reverse thread? Even with the wheels on the ground and someone applying the brakes there seems to be too much play in the rearend. I am afraid I may brake something in the rearend with putting so much force on it. I was going to buy a 1/2" drive 1 1/2" socket for my impact gun but there is no way the impact would be able to get it loose. Any suggestions would be appreciated.
Thanks

get a bigger breaker bar. I've also seen guys take a large crescent wrench and hold the U-Joint coupler to take the strain off of the gears/bearings (use the ground as a stopping point), although I don't think you would do any harm with the "excessive" pressure. Soak the pinion shaft with some PB BLASTER for a few hours or even overnight. The nut is NOT REVERSED THREADS.

:exactly: bigger bar. the torque on the nut i believe is somewhere around 275 lb. ft.

torque multiplier(correct way) or bigger impact gun (way it's usually done)