Check the rear hubs aren't loose. Pull/push tire tops, watch for wobble at hubs. Steering wheel & floor boards look like 66-down some of them had just 1 set screw holding the hub to the axle. Later ones had the same hokey hub attachment just had 2 set screws per hub. Looks like a lot of weight on the wheels, digging puts a strain on the hubs. If they are loose can tear up the axle ends. Finding new hubs also a challenge
Hydro lift hard to find may be hard to find seals, would help to have hydro shop nearby.
Blade is lightweight snow blade not heavier dozer no trip springs
Missing pto try to negotiate that
Check tank for rust at least add a fuel filter. Check motor for metallic sounds at idle, good luck