Wishbone 25 Trailer Wiring Kit 25 trailer wishbone harness kit wit 4 trunk connector. Wesbar harnesses conform to all applicable SAE, NMMA, and TMA standards to provide years of dependable service. Standard 4-way harnesses have an 18 ground wire except where noted. Wesbars 5-way plugs mate with all Wesbar 4-way plugs and will operate all DOT required lights. Complete trailer harness kits include all trailer and tow vehicle harnesses, mounting hardware and instructions. 4-Way Flat 25 Trailer End