2013 f-150 made in CA now in USA manual in gear tree no + - y?
 

On my gear tree I have PRNDM21 I'm wondering what the M does I do not have the manual +- buttons and the dealership said that for some reason it was because it was made in CANADA but it doesnt act like a 3rd gear sometimes I'd be pulling uphill and have the petal to the metal and not go over 2000 rpm then the next time it acts and pulls like 3rd gear. I have no idea what this mysterious "M" does.