Regular cab Long Box or Extended cab Short Box. *I* wouldn't want to tow with a short bed std cab on a regular basis, atleast anything 4wheeler heavy (sub 3500 lbs with a quality, but light trailer, thats different).
I'm guessing its a 4-runner your towing. Whats it weigh? Bet it close to 4500 unless its well hacked. I currently tow with a late model 1/2 ton (reg cab, long box), the truck has plenty of work and tranny to get the job done (even with the "small" V8), but I need to use a weight distributing hitch to get the trailer right and a bigger/heavier truck just makes towing "feel" better.
Long WB is nice for towing, shorter WB is nicer for maneuverability. If you don't need the bed length, look into a 3/4t or so, extended cab, short box. Good compromise between interior room, wheel base and maneuverability towing and not. Lots of good deals on CL if you don't want the newest truck.
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