I have tried for years to figure out year/mov't details of my Speedmaster without opening the case back, but never really locked it down to a definite answer. Any help is very appreciated!

 

My best answer is to bring it to a jeweler/watchmaker and have them open it and end your years of wonderment.

If that's not possible, my best guess is your watch is a reference 105.012 with a type 1171 bracelet with 633 end links.