I had the Privilage Of Operating one of Letourneau Rubber Tired Dozers/Tractors, i dont know the Model, I sure wish i did, we knew them a TD, back in the early 60s i was in the US Army, with a Heavy Equipment Co, at the time we were in France in the Verdun area, we had a number of these Tractors, about 1/2 had Blades & the other had Big Bumper with a Big push Block in the middle, it was about 4 x 4 best i can remember, the ones Push Blocks were geared just a little different, they were faster in all gears, I was a signed to one with the Push Block, all were pulling pans, i dont remember how many yards, seems like 18 yd. all the tractors had 2 big elect winches on the rear, That winch could snap that cable like a shoe string, Loaded you sure had to be careful going down a grade, it would cross friction on you in a min. If you look at how far the Hitch is Behind the Wheel Base you can see that it was like a lever, if the load behind you was pushing on the rear of the Unit, the shift and brakes were air, there was for ever a air leak some where, the heat on the brakes would make the rubber dish crack & the clutch packs out front were all operatered by air, i hauled a Many Load of dirt behind one of those Tractors, There was another Unit working near by that were Running what is called a MRS >< Miss.River Service Tractors, I know not many of you have ever seen one of these rigs, may not have ever hear of them, it was about like taking a big single axle truck, no cab, reg tires in the front & big tall tractor tires on the rear, i think they were geared 2 x 5, had a twin drum winch sort of like cat had at one time, they were setting right behind the Oper, he had 2 levers over his right sholder, they were tuff old rigs, i think they got there name from all the work they did building the Miss. River flood way, i have a picture of one some where, but first i will have to figure out how to post pictures>< Another thing that sticks in my Memory is the Seat><It was & is the best seat i have ever set on, no moving parts, it was the way the Bottom Part was Made, The Back held you in place as these Tractors Bounced along