Well after all this research on the web and a response from an experienced expert who grades car there still is no real definitive answer. I wonder if there is any real providence on cars to ever really know. Water pump life expectancy was not high and most likely a rebuild by an original owner would have been rare. I have seen quite a few pumps and they all were rebuilds. Also there really is no date codes to help.

Attached are a series of pictures of grouped types. The first type I have found in fewer numbers then the latter. They look more like the early 60s pump 2402291 which had a casting number internally under the impeller. IF you look they have the same outer raised ridge, they have internal casting stamps but now 2843290. They also have tags placed in the mold to have the external casting number present. Some have OS id and some not, and some have Chrysler symbol and some not. Any dates look like casting stuff (shift, day month). To me it looks like the 2402291 mold reworked for the new casting number.

The second type is a different mold in that the casting number now part of the casting with a different style Chrysler symbol. These have no internal markings. The only external markings I have found are stamped "-E-3-, E-5 (twice)" reset no markings. One has no Chrysler symbol cast in, but rather a different style stamp.

Crossed hubs have been 2 styles. Impellers vary significantly from size to one and two piece impellers. Will attach pictures when I can resize them.