Towed my last 5er, 10,000lbs , GVWR , for 5 years , 100,000kms ( 60k miles) with an exactly equipped 2000 , 4X4, Quad cab 4:10 .
The only issue with the unit , is the transmission , reverse gear ratio.
When your towing with the truck , loaded to near the GCWR, backing up any kind of an incline, is difficult. To save the trans , shift into 4wheel low.
Running on the I-5 in CA, where the towing limit is 55mph. I got as high as 12.5 mpg. Climbing hills , if the engine RPM is over 3000, you might as well pour the fuel out on the road . Running empty truck would get 16.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.