Tour issue vs custom ordered

I just purchased a 910 D3 driver from someone on Ebay saying this club was used by a PGA tour player who was sponsored with Titleist. I checked the head when I recieved the club and there is indeed a serial number on it. The serial number on the head is stamped xxTxx ( 2 numbers followed by three letters). I thought tour issue Titleist heads were stamped xxxTxxx. Is this club custom ordered or is it tour issue I'm a little confused so any help would be greatly appreciated? Is there any differences between custom ordered and tour issue clubs?

Also to note the shaft on this club is a Mitsubishi Rayon Diamana whiteboard 73 x5ct with the flower band near the butt end of the shaft.