I'm needing to install a 7 pin spade for a trailer I purchased. My 99 3500 chassis cab has never had any wiring outlet from the factory because its a chassis cab. My manufacturers window sticker states I'm wired for trailer brake controller provision w/jumper and auxilary w/heavy duty flasher. My hope is all I need is a plug and play wiring harness from the rear of the truck to the location of the bumper outlet. Anyone have any advice on how to properly make this install ? Thanks