Hi Krucho,
The main purpose of the Danco Underdrive UD-6 is to participate in slow races
:roll: You don't stand a chance with out them. All kidding aside they are mainly used for snow removal(blade & blower). I have the front PTO on my original so I also can use it with my #1 tiller. I have also used it when dirt plowing(high gear low) which is slower than second gear. It just gives you 3 more different speeds to do different jobs. The UD--6 creeper is a gear reduction and the creepers in the NF & WF cubs are planetary reductions called sun gears. These are getting hard to find and the gears inside are NLA(no longer available). Don't shift on the fly. Keep it filled with SAE 140 oil.