On an M if you have the belly pump it is my understanding that the pump has to be lowered to remove the belly pump stub drive puck. So that will require additional time over the same job on an H. There is a replacement two piece drive puck that has a cotter pin that allows removal without dropping the pump. It has been a long time since I looked up in that cavity on an M with a belly pump to see how much room is up there. Mine has live hydraulics and the pump is converted to a reservoir using a special aftermarket plate that removes the guts. I am attaching a video of a gentleman explaining the two piece drive puck.
