I agree with that. At some point the added weight of a 3/4-1 ton, combined with usually a stiffer suspension/frame,
pays off a lot towing heavy (9200 lbs for me, usually). I think the trailer helps also. This homemade deckover has 12" tall, 1/4 wall C-channels for the main side beams. It's so stiff, tows incredible, even at high speeds.
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And thats a damn fine truck youre towing it with.