...  how doe a  12 tooth pinion gear fit in where a  9 tooth  used to be?   This is listed as  a replacement for a  3020, 4010, 4020,  4030 4230  and   7700  combine  with  GAS  OR  PROPANE  ENGINE.

does all those  clocking holes   move the   pinion up or down for  proper clearance,  the mount is eccentric?  

Or is that website  incorrect on the application?