Repowering a Peterbuilt

[the missing link]

The first problem I see that you have is that you run driver's .
The problem is they have the gotta go attitude , like all of trucking 20 + years ago .
This is not 20 years ago .
This is why this is a problem .your losing alot of feul milage and life out of the motor , tires ect.
When I pulled trains up north ( 140.000 lbs ) , most of the time I was getting the same amount of feul milage as the 5-6 axel guys .yes it would take me longer but by very little .
The drivers are paid by mile . I am paid by the net and it's my truck . That's the difference .
If you get pissed off reading this , then your not ready to actually face your biggest problems .
In your case I would stongly recommend a 871 because you can tune it for a driver . This will give you a greater chance for less engine abuse and better feul mileage . Keep in mind in my books making them pull under 1500 at all is pure abuse .
To tell you the honest truth if I was a driver paid by the mile , I would run the shi#t out of the truck . That would make me the most and you the least. if I drove yours like mine you would make alot more cash and I would make alot less . There layes the problem .
I can be wrong about your situation or how your business runs but at first glance that is what's standing out to me .