It wouldn't scare me to pull a 15K # 5th wheel with your truck. When it comes to tow ratings it's all based on the total package. Tire ratings, axle ratios, spring rates etc. The biggest hinderance of a SRW truck is usually the load capacity of the two rear tires. The fact that your truck is powered by a gasoline engine has nothing to do with it. I have owned three diesel pick-ups in the past and I do believe they tow heavy loads better than naturally aspirated gas engines but it's just a question of how much money you want to spend really. The hot ticket for any towing rig would be deeper axle gears and a gear vendors over/under drive unit IMO. Not the cheapest solution but I think it would make these older gas trucks with only 4/5 speed transmissions drive and tow much nicer.
