I'm looking to get a used walkbehind to use for a few yards and as a semi back up. What models and years are a good choice, and what should I stay away from. I would like to get hydro if the price is right. How does the gear drives work? From the pictures I have seen it looks like change it with your knee. I would like to get a sulky for it also. I'm kinda looking for a 36-44". Thanks for any info.