Help! Upper and lower ball joints are too far in new drop spindles?

[SoCoC10]

I installed some 3" drop spindles on my 69 GMC and the outer tie rod fits fine but the upper and lower ball joints are sitting way too deep in the spindle? The castle nut is 5-8 threads past the cotter pin hole. My guess is the previous owner used 71-72 spindles to do the disc brake swap so I need 71-72 drop spindles? Thanks for the help.

Here is a casting # off the stock height spindles I just removed.