I just found GM 365720 and you're absolutely correct. That number is a complete assembly that includes all plates, bolts, and the rubber mount... Also if I am to interpret the book correctly, the original number for the rubber mount only would be GM 606427?...
Great news on GM 3702173 rear mount, but the book also mentions GM 3692956, yet I did not see that listed on the old car manual...Were you ble to find anything on the original number GM 60869? A compilation of some common GM part number changes over the years would always help, especially for the pre-war stuff...
