I believe there was a 46th Infantry Brigade of the MI ARNG under the 38th ID of the IN ARNG. 46th Infantry BDE had a 146th Forward Support Battalion. Under 146th FSB was C Company. C Company was the FSBs medical company.
However, those bumper numbers don’t reflect that. Next to the 38I should be 46BDE, not 146. But units often come up with unique markings that might not quite make sense. I couldn’t find any reference to another 146th Brigade or any 146th numbered echelon that might have a FSB within its task organization. There was a MIARNG 146th Multifunctional Medical Battalion, but I couldn’t find any reference to the 146th MMB being tasked in any way to 38 ID. Plus a MMB would not have a FSB within their task org.