PB Blaster is the only stuff I'll use now. I let it soak overnight (currently doing for a timing belt, H2O, clutch etc). Try some heat on the bolts also. When I did my kids 88, the mechanic before me broke the welded nut free also-he/she must have been crankin on it.

I haven't had these bolts off for 3 years, so we'll see in a few minutes. I have no air tools either. Crank nut is always fun!