No diff, have to come up with your own make shift deal. I don't need it since it's my outdoors car. But other people need a diff to run foams on carpet or to run the Reedy Race where oneways are banned. Screws... I'd upgrade to Speedtech's Ti screw kit. The kit screws will work. But Tamiya "stock" screws tend to strip out the heads sometimes. Mainly counter sunk ones.