the 11988 serial number more likely makes it the 1988th truck because plants always started with something like 10001, although I haven't seen reference to the specific CDN plant procedure .... the body number is the serial ID of just the body, which was installed as a complete unit on a complete chassis
don't know when the mount change happened, but any AD body can be made to fit any AD frame, some take a little more work than others
Bill
