VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 1938 water pump part numbering confusion

I've found a 38 Chevy water pump, here:
http://www.ebay.com/itm/230724360327?item=230724360327&viewitem=&sspagename=ADME:X:eRTM:MOTORS:1123&vxp=mtr
My question concerns the part number. The ebay listing says part # is 598308, which matches the online 1929--1941 parts manual I use for reference. However, the actual # on the pump being auctioned is 598309.
I've searched this site and found a 2003 discussion between 50 Chev and Chev Nut/Chevgene. Gene indicated the 598309 pump was the same as the 598308, but the 598309 was used on the 1939--1940's.
I'm trying to make my 38 Sedan a matching numbers car. So, is this ebay 598309 pump right for my car, or not?
BTW, this is the 2nd time I've seen this problem--about 3 months ago, another 598309 pump was sold on ebay, and as a 1938 pump.

Say, I just noticed I've messed up 1938 in the subject line. These keys are too small for my fingers.

Both the 1937-38 and 1939-1940 pumps have the casting number of 598309 because the actual pumps are the same. The difference is the pulley. The 1938 pulley is stamped 838764 and the 1939 pulley stamped 838905.
As far as number matching goes most 1938's came from the factory with a completely different pump and they lasted only a short time. The newer replacement pump is a sealed bearing pump that does not require lubrication.

Some '38 water pump info: The first '38 pump was Type1 which had an oil cup on top which needed filling every 1000 miles with 20w motor oil. It had 2 bushings and an internal oil reservoir. Its shaft was 1/2" longer, and the pulley assy was 1/2" longer than the previous, similar '37 pump. The 2nd '38 pump was Type2 which had ball bearings and no oil cup. Both '38 pumps had a pulley which was 4 21/64" O.D., which was 1/64" larger in diameter than the '37 pulley. (There were special pulley/fan units for '37 & '38 pumps which increased the pump and fan speed 10% for low speed operations.) The '38 pump can pump 47 gallons a minute at 4000 RPM. These pictures are from a Sept 1938 master parts cat.

And when a second type pump replaced a first they pump a different fan blade was required. If the first type fan blade was used it would contact the radiator. From the info. I have very few (late) 1938 engines had the sealed type pump.

Gene, thanks as usual for the technical info.

Thanks, that was a big help.