The wifes old '06 5.3 4L60e 4wd 1500 crew cab chevy 3.73 would struggle pulling my 7200 lb blue tractor and 2440 lb trailer. I never ran the tranny in OD gear.
Her new '16 same truck with the new 6 speed tranny 3.42 gears much higher HP/Torque 5.3 tows the same tractor/trailer much easier....however I run the tranny in manual. I can do a whole lot better job of keeping the tranny in the 2300-2800 rpm range than GM computer. I run 3rd gear in the hills and 4 or 5 out on the flats
Now..... I tow mainly with the Dodge/Cummins NV5600 tranny so I understand proper gear selection/tranny heat build up and running the tranny in a gear that has less stress on the engine and tranny.
