I am posting for my dad. He has a '98 Chevy 6.5l turbo diesel, 4wd, crew cab, long bed, dually, with a brand new (not broken in yet) stock transmission and torque converter, with a 15,000lb. fifth wheel, new 10 ply firestone tires all around and 4.11 gears I believe. As far as I know, everything is OEM parts. He hasn't pulled much of anything in a pick-up before, though he and my mother have driven over the road tractor-trailers for 25 years. My mom wants to pull an 18,700lb. RV with electric brakes from northeast GA to northwest KY which has a few strong mountains on the route. My dad is concerned about the new transmission. Also the fifth wheel being under-rated, and how well the pick-up will handle such a load. He isn't doubting my mothers capabilities, but he loves his truck and neither of them have experience with pick-up towing. Any information, tips or suggestions would be greatly appreciated. Thank you!