I am at a loss on how to figure out the approximate date of manufactor of these two Hamiltons:

1. model 923, 23j, R1537

2. model 917, 17j, X47967

Can someone help me out?

Donald,

The lettered numbers are at the end of the Gelson list found in the Hamilton Forum.

Here are the links: Hamilton Movement Numbers and Hamilton Horology Reference Materials

Page 22
Page 23
RR

Thanks for the info.