Well, I have worked everything I own to the max...
03 4.8 tahoe, pulled 7k lbs 100 miles on and off, did it like a champ, took forever to get up to speed though, lock it in 3rd gear and let it eat at 60 to 65 mph...
2012 suburban 3.08 gear, loaded to 7k lbs and 800 lbs inside, was a rough...