I tow with a 1500 99 suburban (long wheelbase - stable). Vortec 350, 255hp, 4L65 (custom built 4l60) with 4.10 gears. 18' open trailer. Camaro or Corvette is the typical load. I don't live at elevation (i.e. colorado 5000'+) , but this setup will pull fancy gap VA or Franklin/Otto/Asheville NC without a problem. i.e. it'll stay locked up in 3rd gear (1:1) and maintain 55MPH without downshifting. I've hauled on many 1000+ mile trips (up & down I81). My truck has the tow package, so I have oil and transmission coolers and a heavy duty radiator. Keeping stuff cool makes stuff live. Then there's brakes. The brakes in my rig are marginal. I can barely stop everything with my brakes alone - obviously my trailer has brakes and that helps, but... I don't own a 5.3 but I have friends who have the gammut of newer trucks. I like mine better. The 5.3 needs to downshift too much. The 6.0 is potent, but it gets big block gas milage. The big block is overkill - unless you'd like to tow a 28' trailer with 5000# in it. So with all that BS said - for simply towing a car on an 18' trailer, locally (within 100 miles) - almost any truck will do. For long distance, I'm stepping up to a dmax dually. So I'll be hauling safely & economically. That's a whole nuther story I probably should have started with 1st. Safety. With any SRW truck you have ZERO margin of safety. Regardless of what engine and brake package. I've seen several folks scatter enclosed trailers and I nearly lost a load myself in my suburban when I had a rear tire fail. This is actually me this morning, hauling my 74Z locally (20 miles). Effortless. I get 14MPG doing it too. MPG is important too if you wish to go anywhere.