Dear Rhonda,
Have you looked at the Missouri Adjutant General's Report? This three-volume set includes unit histories and muster roll information, including enlistment dates, where enlisted, etc. One of your major Missouri Libraries should have this.
I also noted a pension record for James Drenning which includes both an "Invalid Pension" and a "Widow's Pension". There is an interesting notation which I cannot read that seems to say he served in both, or either, the 31st or 32nd MO Inf. I've never applied for a Missouri Soldier's pension record; however, I'm sure the Missouri State Archives must have copies of these valuable, multi-page documents.
Finally, have you applied for the "Compiled Service Record" of James Drenning, I also noted he is listed as "James Drining" in Company E of the 31st MO Infantry.
Perhaps others on this message board can give specific instructions on how to apply for Soldier's and Veteran's Records in Missouri.
Jim Martin