The BCM gives the miliage to display as I understand it. You can verify this by calling the dealer parts department.
IF I were to order a bcm through dealer or aftermarket, it would have to be programed. It would require the VIN and mileage to do so. IF the VIN doesn't match from the pcm to the BCM, the truck would start and stall as the fuel would be stopped. There are two ways of replacing the BCM. Either yours is removed and sent in to be rebuilt along with the needed info or one is rebuilt and programmed with your info. Service techs do not program these, the rebuilder does.
It is possible they gave the wrong mileage when it was reprogrammed is my guess or they installed a used bcm and pcm. Someone made a mistake it sounds to me. Who? Is the question. According to your figures your drove about 1000/wk. Or someone screwed up.
The BCM and PCM would need to be reflashed to change the milieage. But I doubt anyone would be willing to do that due to liability of odometer tampering.
I hope that clears things up, if not feel free to ask.
Thursday, January 8th, 2009 AT 5:32 PM