Seeking Records of US Army Remount Service Panama Canal Dept WWII

Researching my grandfather's WWII service, never talked about it in his lifetime and died of cancer in 1977. I learned that his records were probably destroyed in 1973 NPRC Fire, but I did manage to learn he was assigned to the Quartermaster Corp under the Panama Canal Dept. If anyone knows the record group I should look for it'd be much appreciated. He enlisted in July 1940 and left in September of 1945