i did not know that 40 tooth was stock (bought the truck on ebay), and yes it came to me with a 38t. i can easily buy another gear. would that still be over geared? i looked briefly on the traxxas site and did not find anything bigger than 40t, is there another option. i already have the 18 tooth pinion and was looking for a cheapskate way to lower the speed. i should have double checked Brian g speed calc