Please note: This SJM215 main gear will not work on the stock SJM180 as the retainer pin hole is larger and uses an M2x8mm fastener. If you wish to use this main gear and update the stock SJM180, you must also use the SJM215 (SP215022) main shaft and one M2X8MM countersunk screw (SJ30005/SJ30013/SC215012).