Kubel,
Yes the 66th and 67th Armored Regts of the 2nd "Hell On Wheels" Division used some M4A3s with 75mm guns. They would have used the standard markings of turret stars (usually obscured or painted over), the tank serial number on the side hull rear, the unit marking in the right front & left rear, and the tank company and number on the right rear & left front. However, most of their tanks seemed to have most if not all markings obscured.
Hope this helps!