Thank you for your reply, PJW 
So, it is possible that he was sent to this company to recover from his wounds?
Maybe - due to his wounds - he was sent to "light duty" untill recovered enough to go back to the frontline units?
He was with assault engineers or special engineer brigade on D-Day.
But somewhere in France, he got shot up pretty bad (back, arm, leg) due to a grenade or mortar shell or something exploding nearby.
It wasn't so bad that he needed to be transferred to the US as he ended up in the 981st till December 15 when he was transfered to 26th Division (328th Regiment) as a BAR gunner.
I'll ask him if he got documents mentioning his unit at the time of D-Day.
Maybe he has them still ..... or they're on their way over to me as he sent me a postcard telling me he's going to send "a box of goodies". 
I have his engraved Purple Heart and Bronze Star which mean more to me than the the rest of my collection together.
Erwin