[OG68]

My 06 Silverado 1/2 ton (170,000 miles) pulled the 68 for 700 miles with no problem. 290 HP 5.3 / 4L60 / 3:23.
Car and truck bed had everything in it except the engine.
50-55 in second gear up the Grapevine hill (6-7% grade for 7 or 8 miles). I just got in line with all the faster trucks in the #2 lane.

Just took my time, stayed in the slow lane (required in CA) and transited Los Angeles rush hour traffic without a hitch.