Found a Johnson POL-15 S.n. 637140. I know Johnson made POLR POs and standard POs. This one is a standard PO length shaft, not like a VL-45… Anyone knows what a POL-15 is? It looks like a standard PO
POL-15 is a standard PO with long shaft. POLR-15 is a military PO with long shaft and reversing capability. The rope sheave might not belong to that motor or it may have been converted to short shaft. Also, there are one too many numbers in your serial number. Serial number is from the 1948 model year.