https://trustytimewatch.io/index.php...mt+gsf&x=0&y=0
The movement is the first generation VR GMT, what RWI calls the VR3185 since it is modeled after and operates like the gen 3185. The main difference between the gen 3185 and 3186 is the jumping hour hand module (jump click), which is more robust in the 3185 though it operates with a slight hands wobble. That is why it was redesigned, and because the new one breaks more easily Rolex is on its third version of the new part.
Gen jumping hour click springs compared
The newer next-gen VR3186 is also based on the gen 3185 (good news for us) and has only a modified balance assembly with a deco plate on it.
Both the VR3185 and VR3186 are engraved 3186, which is wrong for all 126x GMTs - it should be 3285.
However, this VR3185 is a great and reliable movement which I will take any day and will continue to source even over it's nearly identical successor. The VR3185 is easier to regulate due to the position of the regulating arms.