My dad has a woods finish mower model RM59. He asked me to try to find a manual for him. I noticed that when looking for a manual, there are three seperate manuals, one for a RM59-1, one for a RM59-2, and one for a RM59-3. The only thing that I can get off of his is plain old RM59. Could someone tell me what the difference is between the three?