In reading these messages it is very true that what's on a soldiers discharge may not be whole story as to their service. My dad's discharged show him as being with Company C, 648th TB Battalion. But he was only in that unit for Two months prior his discharge in Dec. 45 He was transferred to this unit because he didn't have the points to come home. His prior service was with Company C, 131st Ordnance Maintenance Battalion, 9th Armored Division from July 42 to Sept. 45. I discovered this out based on Two things, A photo taken of my dad early in his service in his uniform with a patch of the 9th Armored, and my Mother recalled that the number 131st was on his letter he sent home. With this info I have discoved alot about my dad's service.
So any small bit of info might get you going in the right direction.