Where is the number located? They did come off of a 66 drum brake car but with everyone swapping stuff I'm not sure if they were the later spindles or not.
Check this link for measurements of the ball jionts (small vs big). How to tell '73-up UCAs?
If you look at the pics in the link above it appears that the small ball joint (where it fits into the spindle is 0.55" thick vs the large ball joint which is aprox 0.62"thick. So if you had a caliper you could measure the thickness of the ball joint (area that fits into spindle).
