Hi this is my first post so please excuse any missteps. I am trying to get some info on a Hamilton wrist watch with a 10k gold case 27mm x 30mm and the following movement. I'll try to attach pictures. I believe the movement model number is 987A and the serial number is 0160139. I acquired it as part of a group from another "collector". Although it's running great and appears in great shape, I doubt it's been serviced for decades. Based on the style, I'm guessing it's from the 40's? The case number is 1253066. It also has what I assume are watchmaker marks etched in the back. One states GL, A4148. The other states 8M61CM. The 6 could be a 4. How can I determine the age of the watch? And any other information you can provide would be appreciated. What do the marks mean? I'm relatively new to collecting (not in age but in the hobby). I've done a few searches but haven't found a lot on Hamiltons. I have a number of early watches so even If you can direct me to another resource it would be helpful. Thank you!