Here's a video,of a '52 G.M.C. 450 Tandem. It has a vacuum switch,for wet/dry pavement,but no HI/Lo. This one is equipped with ,(I think),a 5-speed. Walking-beam suspension,and hydraulic brakes http://s1181.photobucket.com/user/willybickey/media/7-3-2013/MOV00219.mp4.html?sort=3&o=1.

Just sold: 1955 2nd Series 6500 2-Ton Flatbed Truck
Mo' Tater
In the Stovebolt Gallery
More pics and videos on Photobucket

It takes an awful big dog to weigh a ton.