Amazon: trailer harness extension SUZCO 25 Foot 4 Wire 4-Flat Trailer Light Wiring Harness Extension Kit, 4-Way Plug 4 Pin Male & Female Extension Connector & Wishbone-Style with 18 Gauge White Ground Wire with SAE J1128. 4.2 out of 5 stars 62. $10 $ 10. 99. Get it as soon as Tomorrow, Oct 17. Amazon: trailer light wiring harness extension: Automotive Kinstecks 60Inch 4Pin Trailer Wire Extension Hitch Light Trailer Wiring Harness Extender for LED Tailgate Light Bar Trailer Lights and Other Use. $9 $ 9. 99. Get it as soon as Wed, Aug 7. FREE Shipping on orders over $25 shipped by Amazon. Only 5 left in stock - order soon.