Heaviest GVW on a square body?

[kennyw]

I have an RV conversion Cab/Chassis with 10K GVW but they added 15K rear springs.

[bigdaddy4x4]

i had a 86 c30 454 4 speed roll back with a 17 ft chevron steel bed with stinger i was hauling for sadisco now called copart when i first started in 1987-95 it was rough to haul to 2 at the same time the truck would pull anything but alot of the cars trucks would be very hard on the rear stinger to pickup high enough to tow i went to a spring shop and had new heaver springs added to the rear and after adding the springs it would pickup any thing you could put behind it i am talking like 2 77 cadillac sedan devilles one loaded to the rear and picking up the other from the front i was hauling 8 to 10 cars trucks a day and never had to go thru the scales of course that was years ago but i wouldnt be afraid to build a c30 today if you aint gona be useing it everyday