Hi Gino
I did a lot of research on Korean War recently. I also look for crews for my M40 and M43 GMC/HMC. For the summer month, I would suggest M1943 trousers with T-Shirts or bare chests. I think I ues the torsos from Tamiya`s old 25 pounder crew. Although I found no pics of winter Arty crews the Parka type jacket with pile cap would be most likely. And how about a late war crew with body armor?
BTW Masterbox announced a crew for the Long Tom kit. Not sure when they will be released but they might be a good start.
I gave Masterbox some images of Korean War, lets hope they will use it for good.
HTH
Hans-Hermann