One of my rear wheels for some reason, is out of spec by 0.5 degrees and can't be corrected. Is it possible that shocks could be worn ultimately causing this slight error? It's an '01 with stock suspension and sub-frame axle bolts, 93.5K miles.

 

No. Shocks don't effect alignment. They damp the springs. If they weren't there, after every bump car would just keep bouncing down the road.

It could be the rear subframe alignment. The subframe bolts to the body. There are 6 large bolts that hold it in place. There are two alignment holes in subframe that are supposed to align with corresponding holes in the body. You stick something like a fat Philips screwdriver into these holes, and make sure it can go straight up througj both holes. Both holes align.

If they don't, you loosen these 6 bolts, use the screwdriver to slide the subframe around until the holes align, then torque the 6 bolts back down.

Then go for wheel alignment again.

 

A blown airspring in a monotube shock will change ride height by? Idk...like 0.25" or less.

Your camber is adjusted as far as possible...but is STILL 0.5" outside of adjustment? Is that correct?

 

Do the alignment bolts still turn 360 degrees without too much effort?
You never hit a curb, did you?