Farmall B Wiring Harness - Steiner Tractor Parts Farmall B Wiring Harness found in: Wiring Harness Kit (for tractors with 1 wire alternator), Wiring Harness Kit for tractors with 3 terminal cut-out relay, Wiring Harness Kit For Tractors Using 4 Terminal Voltage Regulator, 6 Volt. farmall b wiring harness | eBay Save farmall b wiring harness to get e-mail alerts and updates on your eBay Feed. + Items in search results. FARMALL A&B WIRING HARNESS. PART # 51998D. LIGHTS & REGULATOR. BRAIDED. Brand New. $55. Buy It Now +$7 shipping. 69 Sold 69 Sold. FARMALL A&B WIRING HARNESS. PART # 51998D. LIGHTS & REGULATOR.