Wiring Harness for 1999 Ford F-250 and F-350 Super Duty Free Shipping on Orders Over $99* Only 9 Hours 50 Minutes Remaining *Available Within The Contiguous USA. Wiring Harness for 1999 Ford F-250 and F-350 Super Duty. Question: My trailer wiring pigtail has been cut off. The plug and hanging colored wires are there, but I need to know what the color codes are and a diagram of this model of the4.8/5(216) 99 ford f350 wiring harness | eBay Find great deals on eBay for 99 ford f350 wiring harness. Shop with confidence. Skip to main content. eBay Logo: Trailer Wiring Harness For 99-01 Ford F250 Super Duty F350 GW21X4 (Fits: 1999 Ford F-350 Super Duty) Hopkins Plug-In Simple (R) Vehicle Wiring Kit. Brand New. $27.