I currently have 4.5 degrees @ the bottom "spring mount",front pointing up. This would mean a 10.5 shim.

If I'm not mistaken, caster is supposed to angle upper part toward the back. For the sake of argument if the pinion is rotated up to get the 6 degrees you mentioned, that would put the pinion flange @ 12 degrees and that seems odd. I'm not implying it would be wrong, It seems strange.

I think I will try to eyeball some 84-85 trucks locally.

\Thanks Roger.