I have a case 646 loader tractor,I would like to take it to the lake and get some work outa her. Problem is the lake is in the mountians with very steep access roads. I do not for see a problem going up the hills,coming down is the problem. I have read about the newer tractors having a holding valve,would this help out with the braking? If so would any one know where to get one? or could I get an after market valve. I have never seen one so if some one had a picture of one that would be appreciated.