Just look up any of those early chevys or dodges and they will have the nut shaft. Get one at napa or other parts store. It should look like the one you took off. They even sell them a little cheaper without the reservoir since you already have them apart. We in the core business call the early saginaw pumps like that a nut shaft and banjo can reservoir.
I think I'll get a nut shaft with the reservoir. They have them at the local parts store for $48 not bad concidering i was looking at the new wild horses unit and bracket for about $200. After scraping the sludge off mine it's apparent somone did some brazing to the return to fix a leak. Think it's still got a pinhole.
Thanks for the help on this.