Building a truck for towing 10k pounds

[Alex V.]

Yes, a body swap to a 90's-2000's diesel chassis would net the most capable vehicle, but I think what you're wanting to do is well within the limitations of a properly equipped, mildly modified 67-72 1-ton. My FIL's '03 1500HD is rated within 1,000 lbs the same as my '85 C3500 for trailering - 10.2K and 11K, respectively - that is to say, a modern 30-series diesel is borderline overkill for a 5 ton trailer. Starting with a 30-series SRW big block truck, probably '71-72 would be best, and making sensible brake upgrades, possibly some frame reinforcement behind the rear axle (btw, is your trailer gooseneck or bumper hitch?), and a mild 454. Really, a Vortec 454 probably develops enough power stock to make due, and with mild "warming up" will make 450 lb.-ft./tq, and a stock TH400 will hold up for a while, not to mention a properly improved 400 or 4L80. It'll ride like a lumber wagon unloaded and get 11MPG at best, but it'll be up to the task.

My '85 is a SRW 454/TH400 with 14 bolt full floater, 4.10 gears, hydroboost brakes with disk front and 13x3.5" rear drums, and standard-rate (3,500?) lb. rear springs. I brought a trailer weighing roughly 9,000 lbs. 450 miles from Missouri, with no trailer brakes, and didn't feel that it was too much for the truck. No, it wouldn't stop fast and I was astounded my old, leaking transmission made it, but the chassis had it well under control. The '85 drivetrain is nearly identical to, and the chassis isn't light years away from, an early 70's truck optioned similarly, so I feel performance expectations are somewhat comperable.