Friggin pinion nut not breaking loose....

Hey folks,
Planned on pulling the chunk (742) to install a suregrip and 4.30 gears set. Figured I'd break the pinion nut loose before starting. Got the car on the lift, PJ Blaster, parking break on, breaker bar with extension. Not budging. So much so that the parking brake isn't holding it. No problem, wedged 2x4s between the lugs and the ground. That stopped them from moving. No luck breaking it loose. Springs flexing but that frigging nut won't break free. Put a floor jack on the end of the breaker bar to get more leverage....nope. Was lifting the car off the lift and boards were cracking. WTF. Knew it'd be tough but geez! Soaking it overnight and will try again tomorrow, maybe heat it a bit. In the mean time, any ideas?

I guess worse case I'll just pull the chunk and bring it to a shop with a big *** impact. But that's pain in the butt too.

Thanks for any suggestions...

Pat