Dan,
I told ya it looked like C3 Corvette a month ago. To be fair I said there is 2 hubs the Vette uses but did not know if you had small or large bearing hub. If you want to spend $$ ask for Vette parts but they are the same as items listed for Camero and the El Camino only cheaper. Go look at this article, it talks about the interchange between other Chebbie but show the obsolete 1 piece unit etc...
http://www.enjenjo.com/techart/70impaladisc.html
I do have the larger bearing hub/spindle assembly and maybe a small hub for comparison only. They fit chassis's in the works but your welcome to borrow for a while. If they are right for you I have all the component part numbers to save you a little research time.