Oxbow can I ask what weights you have on the tractor. Problem with our truck is the neck is to short to put enough weight on the steer axel.
The picture is a little deceiving from the angle that it was taken at, but we have two holes in the neck of the lowboy for the kingpin and use the front one. The center of the fifth wheel is directly over the front drive axle, and with the tag down (depending on how much air is in the tag air bags, I can adjust as needed) we can get 12,300 lbs. or so on the steer axle. I have about another 6" or so of fifth wheel slide going forward, but the clearance between the back of the tractor and the lowboy gets a bit close, and the steer gets too heavy for my liking.
This outfit weighs about 41,000 lbs. empty, and with the D8T we were 137,000 lbs. +/- gross if I remember correctly. I didn't scale this load particular load out, but from experience I should have been about 12,300 on steering, 11,000 on tag, 49,000 on drives, and about 65,000 on the trailer. I did have to get a special permit for Montana (where the photo was taken) but I can haul this under my annual permit in Idaho on the majority of highways and the interstate.
The old tractor is pretty well set up for this with an 18 speed, 46K 2 speed rear ends (4.11/5.29) and Hendrickson pad suspension, and handles the load pretty well.
