6 inch pulleys front and back. Locked rear end by adding a extra gear works better than welding.
Murray's are the best to use as they have a strong C frame.
Working on a MTD now but because of there center pulley you have to just change the front pulley to a 10 inch
What do you have for tires, are they low presure. How does it handle the mud? It looks like a fun time. I run off road but have two ATV's.