just tried zeppin mbl kevlar belts(similar to mugen rubbers), lots of free roll as long as long as
the front rears and side are on the loose position,! urethan belts last longer if theyre on the tigh position so no free roll on those but on the other side no teeth misiing
up to two gallons of fue on the car with stock gears l with 60k diff oil on the rear but every 2 liters, change of diff oil!!
, i guess that if you rotate the diffs front and rears left to right specially if you run clockwise only, can give you up to 3 gallons or even more on on set of stock gears!!!