73-76 upper control arms for disk brakes

Please help this idiot! Yes, that's me. I am a 30 year veteran of restoring Pontiacs, mostly GTOs. I got bored with that routine and branched out to Mopars, as I have always loved them. Anyhow, on my first project restoring a 69 barracuda, and bought a disk brake setup off of a 73 Dart Sport at the junkyard. As I started my suspension rebuild, I removed the ball joint from the left upper control arm by pressing it out. Imagine by surprise to discover it was threaded! There aren't enough threads left in that control arm to safely reuse it, so I need a replacement one, of course, will be willing to buy the pair of uppers for a reasonable cost.

thanks

Jim