We just took delivery of a 2010 International truck. It is a 4400 seiries with 2000 gallon of water. It has a 6 speed transmission. My question is should the 6th gear be locked out? We are in southern Ohio nd we have a lot of hills in our area. Our sales rep says we should have the 6th gear locked out to give it more power on the hills. What do you think? Will this help?

