One of a kind water pump?

Its broken! Oh no, now its really one of a kind.

The cast iron ones are a dime a dozen, lots of suppliers have them. The unique thing here is the one 66Signet has is aluminum. These, to the best of my knowledge, were never offered stock in any automotive application from the factory. I have been on a 20 plus year hunt for one of these and did see what appeared to be one on Ebay about 10 or more years ago but it got bid up and went pretty fast. I agree it could have been for a marine or industrial application but pretty uncommon. If anyone has any information on these these please share.