Rear Sprocket #420 60th Fits Hammerhead Go Kart 80T, Mudhead 208, Trailmaster Mid XRX, Mid XRS Bolt Pattern=4x80 (57mm to adjacent hole) Shaft=39mm OD=9 5/8 : Get 2 It Parts, LLC offers SAME DAY SHIPPING. FAIR PRICING. SOUTH CAROLINA WAREHOUSING.