The seller has 2 part numbers an early version and a later version2. they are different master cylinders. WHAT DO YOU THINK! 3. FOR EXAMPLE B7A-2140-A HAS A 1 AND 3/4 INCH VERTICAL MOUNTING HOLE! B7A-2140-B HAS A 2 AND 5/16 VERTICAL MOUNTING HOLE. THE SELLER ANNOUNCES THE CORRECT SIZE OF MOUNTING HOLES OR RUNS FROM AMAZON BECAUSE THEY ARE STUPID TO CHECK YOUR TIME AND MONEY.