I have the 4.3 and still run a stock radiator. At first it ran a little hot if I hammered on the motor, but now I am running a giant slimline fan and never goes over 190. I do use the motor real hard when playing in the mud, just gotta make sure the radiator stays clean. I would recommend changing over to the auto trans. I have driven standards off road for almost twenty years and finally switched to auto. I'm loving it...
