Buy, or borrow a BIG pipe wrench, like a 4-footer or so, and hold the pinion flange with it, with the handle braced against the floor. Then use a 3/4" drive socket, breaker bar, and cheater pipe to turn the nut. I've also slipped a cheater over the pipe wrench handle at times, when I was working on 18-wheeler pinion nuts in the 1200-Ft/lb torque range.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!