there is a total of 21 mounting holes; 2 w/0.064 in. nom dia; 4 w/0.156 in. nom dia; 3 w/0.371 in. nom dia; 2 w/0.172 in. nom dia; 2 w/0.400 in. nom dia; 2 w/0.344 in. nom dia; 2 w/0.371 in. nom dia; 2 w/0.187 in. nom dia; 2 w/0.188 in. nom dia rectangle