'66 control arm nuts fighting re-assembly

[Railroadman]

Trying to re-assemble the upper and lower control arm shafts. Os others have experienced, getting them off was a total bear. How I'm having trouble getting the outer nuts started into the control arms. They either want to cross-thread, or I get about 3 flats around and it pops back out.

It appears the threads in the holes are either a bit nutzed up, or maybe obstructed with primer and/or sandblast residue, altho I cleaned them out as best I could. I put a wire brush on my drill and ran it through a couple times but it does not seem to make a difference.

I did a search and found some threads on tightness of the finished shaft, but I can't get there from here yet. Any suggestions? Do I need a giant tap to clean those threads?

TIA!

Edit: OK, I was going at it in the wrong order, was trying to start one nut first. Got the rubber and the shaft in the arm and that centers the outer nuts. Duh - I should'a seen it. Thanks anyway!