Water Pump Warehouse?

I heard back from these guys. They list 4 pumps in the early smallblock configuration, 2 part numbers & then the same 2 part numbers, each followed by the letter P. I asked what the differences were in the pumps. They said they didn't keep stock of one of the part numbers so they couldn't tell me what the difference was between it & the other. They said that the "P" pumps have a.... "closed back impeller installed with tighter tolerances.....020" clearance vs. .100 to .050 for the standard pump." This sounds a lot like what Flowkooler does with their pumps.

I haven't checked shipping prices but this seems like it could be a decent alternative to the Flowkooler pump for people with the early cars that want to stay with the left side inlet.