072500hd

Does anyone know how to re-program a speedometer odometer from metric to English. I took my truck to get radio swapped out, the mechanic couldn't make it work, i took it back with Shawns info posted here and he programmed it ,but later that day when i filled up the truck and went to reset my odometer and noticed its now in Metric. I do not have the Silverado package with the extra switches that allow you to toggle between options, and there are no wires for the upgrade behind the dash panel.
I need to get this back to English before the end of the year and hate taking it back again to the dealer. All the mechanic said was he didnt know and i should unhook the battery, that didnt fix it.