How do you remove the rear spindle/knuckle bolt?

I am trying to upgrade the rear brakes of my '96 hatchback to the larger 4-door sedan rear drum brakes. This upgrade requires the removal of the rear spindle/knuckle assembly. But I am stuck like Chuck and my name ain't Charley. My question is: How do you get the bottom knuckle bolts out? I have tried beating with a hammer and an impact wrench and I can not get it to budge! Any ideas???

Thanks, Shimaze

PS> Is anyone parting out a '95+ four door Metro?

Sometimes you have to use heat from a torch to get stobborn bolts like that out unless it has rubber bushings inside. Lots of penetrating oil and patience can let you win.