I'm in the process of rebuilding my front end (it's torn apart right now). This morning I had planned on taking my A-arms in to have the joints and bushings swapped when I realized I received two different ball joints in my front end kit (the one from fbodymotorsports). So which one is the right one? Looks like I'll have to order another one on summit (or just order a new matching pair).

They both look the same to me, as far as being "right"; just, one of them has the "wear indicator" feature, and one doesn't.

2nd one looks like the set I swapped out on my bird from Advance auto

Difference looks jsut to be the boot and grease fitting

What if they're different lengths? So they're fine, eh?

Right.

The one that's got the big hole in the bottom is arranged that way so that as it wears, the grease fitting sticks farther and farther out; that way you can just look at it and see when it's used up.

Other than that, they're pretty much the same. The actual "guts" are the same. The only difference is around the sheet-metal plug in the bottom that holds in the grease.

Very well then. Tomorrow I'll have those pressed in and finish up the front. Thanks for saving me from making a pointless purchase.