Looking for WWII US Army Signal Corps info

My grandfather served with the VI corps during WWII, he was in Africa, Italy, I believe he was also in France and Germany. He brought home postcards from the various contries he visited but he also brought back photographs back of German soldiers. I am thinking he was placed with the 75th division and was in the 575th Signal Corps. AMong the photographs was a picture of a truck and on the front bumper it went like this “VI575” I am still not sure if it reads 57S or 575. When I can I will submit that photo.
Thank you.

Hi Bully, did you ever figure this out? Let me know if you need assistance with submitting the photo. Thanks.