Truck pulled great with a car/truck and car hauler trailer. I got 12-14 with 4:10s. A little more if I kept it at or under 65 mph. I seriously hated to see the truck go. The 6.5s cant keep up with a duramax but they can get the job done for a lot less money. You do need to be careful though as they have a number of problem areas (PMDs on 94+ models, broken cranks due to bad balancer, overheating). This can all be remedied though if you understand the 6.5's quirks. The Diesel Place has a great 6.5 forum. Check out the stickies before you buy.
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2006 2500HD, RCLB, 4X4
6.0, 4L80e, 14 bolt