Since it's in the CUCV forum, I'm assuming he meant M1028A1. If he really means an M128A1, its a 12 tone semi van trailer with full width back doors. There is a 12V lug terminal just to the passenger side of the brake booster that has plenty of amperage however it is not switched with the ignition. You could hook your relay up to that to provide voltage and then switch he relay with power from one of the fuses under the dash. Use a 12V test light to determine which one has the power you need (accessory, ignition or constant).