Drop Spindle Compatibility

[rustbucket67]

So I got a Early Classic 4/6 drop kit, and I've got the spindles installed when the castle nut on the ball joint starts turning turning the stud. There was no point of increased resistance to make me think I had broken the stud loose, and the castle nut is well below the point where you would put a cotter pin through the hole and align it with the slot (the hole is now above the top of the nut.) PO said that he replaced the "suspension" with one from a '95 van. I'm wondering if the '95 van/truck ball joints use a longer stud, and if just stacking some washers/spacers in there will do the trick. This is happening on both the to and bottom ball joints, and I'm not really looking to replace all 4. Thoughts? Advice? Help?!?!