Technical Ranco heater valve help, please.

A while back I bought and rebuilt a heat control valve that I thought would fit my '56 Pontiac. Turned out to be the wrong one!
Can anyone tell me which one I need and what this one fits? The one I have says Ranco HF or Type HF.
Thanks!
Johnny

 

Isn't that the same fire wall shape as Tri 5 Chevys? If it is, then check out Chevy catalogs as there available in the aftermarket.

 

Is this what yours looks like?
www.ebay.com/itm/PONTIAC-HEATER-CONTROL-VALVE-1955-1956-REBUILT-RANCO-RAT-ROD/223235433841?hash=item33f9de6571:g:GX8AAOSwzGBb8GOD&frcectupt=true
KK

 

Yeah.... but so does the wrong one! It's just a little off in size and mounting holes.
Not something I'd be able to tell just from pictures. I'd like to find a rebuldable one for my car that I could afford. Rebuilding is challenging but fun and well worth the price difference to me.
Regarding the tri-five Chevy ones, they're quite a bit different.
Thanks for the replies so far! Ideally I'd like to identify why I have and sell it to buy the correct one.