Help me make sense of this spindle/ball joint issue I have going on please..

[im4darush]

I ordered a lowering kit from western chassis with spindles. My truck is a 72 with original suspension. I took everything off and am replacing it all with 73+ stuff. Ordered all new 73+ control arms with ball joints. When I ordered the kit, I told them I needed 73+ spindles. Kit came in, box says 73-87 lowering spindles part number 13100. So that's good. I go to install the spindle and it will not go on the lower ball joint. Hole in the spindle is way too small. I try to set the spindle on my original 72 control arm, and it fits like a glove.
My understanding is that the 73+ ball joints are larger diameter. When I look at my new control arms as compared to my originals, they are in fact larger with a different taper. With that said, is it safe to assume western sent me the early spindles even though the box says 73+?

I called and explained, but the guy on the phone did not seem to understand, and kept saying they only have one type of spindle. Very frustrating.