I have identified at least 4 maybe 5 James Bakers in the 1st Missouri Eng. The most likely appears to be a James A Baker left sick in Hospital in Nashville Feb 1864 then re-enlisted as Veteran Volunteer in Apr 1864, sent to St Louis to receive furlough same month per SFO # 102. Suffice it to say the muster records are a scrambled mess. I think he would have spent time in McCullom's Home Guard (Indpt Company) in mid 1861. If so he would have been 32 at time of enlistment in 1862.
Clearly have one Baker in Co B and another in I and a third in D.