This transmission will fit the 2011 ScooterX Powerkart. This is also a replacement for older models 2005-2010. Chain must be shortened to work with this gear box, top speed will be increased by 7-8mph. This comes stock with a 7 tooth sprocket. Mounting holes are 2 ¾in (72mm) center to center. Bell Housing I.D. 3 1/16in (77.5mm)