Ball joints on a lowered spindle. Which one to buy?

[ab_70chevy]

I got my '70 2WD from my dad. When i got it, he had already put lowered spindles on it, but he can't remember which ones he put on. Now im trying to replace the ball joints and the new ones aren't wanting to seat all the way down into the spindle. How can i tell which ones i need? The new ones are just about 1/4" too short. I assume i need a different year but i can't tell.
Thanks fellas
-Andrew