Replace# M390259 master cylinder is made by aluminum material. The piston diameter of this one is 1-1/8 inches & 40mm. It has two outlet ports in one side: the forward one is 9/16-18" and the rearward one is 1/2-20". There are many intercharge numbers: 18021273, 18029967, 18M1492, 19176102, 4778450, M390259. And also the superseded part numbers are: 18030956, 18M714, 19176102... As for the fitment, please check the above details:
