Try this listing at the Missouri S.O.S. Archives.

Name: COLDERON, JENNINGS I.
Rank: Private
Conflict: Civil War
Side: Union
Type of Unit: Cavalry
Organization: Missouri Volunteers
Name of Unit: 16th Regiment Cavalry Volunteers
Alternate Unit Name:
Company: K
Period of Service:
Commander:
Note:
Record Group: Office of Adjutant General
Series Title: Record of Service Card, Civil War, 1861-1865
Box: 17
Reel: s833

Also see this listing.