front upper shock bolt doesn't wanna come out

[1966]

I must be an idiot b/c I cannot get out the front upper shock bolt. I've got the nut & lock washer off the back (inside the frame), I can spin the bolt around and around with a wrench on the other end, but the sucker will not come out of the frame. I've been whacking it with a mallet on the inner-frame side trying to push it out of the hole but it's not moving (only have about 3" of backswing to hit it due to headers). Is there some mysterious component I'm overlooking?