Ball joint socket size

Alright guys, I've struck out twice now on Ebay purchases of ball joint sockets. I need this for my '66 300. Measuring ear to ear, the ball joints are 2 1/8". I just received my second purchase, that is actually stamped "2 1/8" " and it's too big. Are the measurements supposed to be the barrel of the ball joint head? What size would be correct?

If anyone needs one of these big-ass ball joint sockets, let me know. Otherwise, I'll be using it as a deep water sinker for striper fishing!