What does ICQ number mean? Secondly, how do you change you user name? You see I am so used to dealing with the vin number, (I have a 65 Mustang convertible) I thought the last four digits of the vin number were the number of the bullitt production run. Last weekend when I washed my car, I saw the sticker on the driver's side inner fender/ shock mount. Mine is actually 03703 not the last four digits of 4500. Thanks for any help.