Thanks gtk for the part number and the lead on the other web site. I got to NAPA before getting your info--however, the NAPA people came through again. The counterperson found the correct waterpump for my truck in their catalog and ordered it for next day delivery. The part number for my '49 was 58-459 ($49 less $3 core). Thanks to the info you provided on the other web site, I understand that my engine calls for the non-by pass waterpump (and probably explains the difference in part numbers). I've installed the new one and am back on the road. The old waterpump on my engine was the by-pass type and was therefore slightly different from the replacement--confusion did not reign because I read the article you recommended!
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