The only information I was told about this picture is that my grandpa (right) was in the Korean War and that's the time frame and location for this picture.
I can't find an exact match for his uniform online so I was curious if there was any other information the historical experts of Reddit may know about the picture. He recently passed away and didn't talk about his past often. Thank you for your help!
The patch on his shoulder is the main variation of the patch for the KMAG (Korean Military Assistance Group).
The uniform is hard to identify in the picture, but doesn't appear to be the coveralls worn in that era due to a lack of shoulder straps, and also the placement of the pockets. Some coveralls lacked shoulder straps but most had big pockets on the front of the hips. It very well my be a standard HBT cotton twill field uniform, it seems that he is wearing a belt that is the same color as the trousers. Also his boots are shined and collar seems somewhat crisp, indicating the possibility he is somewhere with access to good washing facilities.
The lack of rank on his sleeve or collar leads me to believe he held the rank of Private.
Side question-- what about the uniform on the other dapper gent in the photo?
Looks like standard OD utilities for the Korean War era. The OD shirts were tucked in and I can see belt loops on the trousers.
I assume you mean the green uniform. Was your grandfather in maintenance? That looks similar to the coveralls I wore while in the Marine Corps, with boot bands sewn in for the boot blousing. I don't have references or anything, so this may be anecdotal. Try looking up military coveralls, used by aircraft maintenance personnel.