Having done a little research...it looks like the Comair flt is on a 900 from DTW (12 open in F). 900's will arrive at a Jetbridge gate in A Concourse. The outbound STL is a Chautauqua flt. Those USUALLY also operate out of A. There are a few Chautauqua flts in C...but, not that many. Your chances are good that both flights will be in the same concourse. (BTW..I work in A)