Old house with old plumbing..Can't find part

[coryhynes]

Hi,
I live in Ontario Canada in a house that is approx. 40 years old. The other day I had a leak in my bathtub faucet (the piece that turns on the shower head). I tried to remove that part to replace a seal but the threaded area broke and now I am unable to find the piece anywhere. Anyone ever seen this piece before and know where to get it? please see pics.

thanks,
Cory

 

[journeyman]

Install a new valve that one is done

 

[Mr_David]

just looked through a PartsMaster stem catalog. maybe a 1,000 stems and no match. Some close, like Crane, Syco, but not the one