I recently bought miniart's US tank crew titled "close combat" and needed help with the paint color for some of the crew members. Most wear an overall style and the instructions label them being painted a generic grey. Is this correct? I'm not familiar with this style of uniform on tank crews. Any assistance would be helpful for the appropriate color!

Vallejo make a set of highlight and base colours in their Panzer aces line for US tankers, but somewhere around a buff-earth colour should work.
try this site for reference
http://www.usarmymodels.com/guidetopainting.html