I've "heard" that story about the light control switch being left on draining batteries but I've never really proven it. Our trucks (still got seven CUCVs) sit sometimes for 30 days at a whack, still don't draw down. You can test it by disconnecting the one side of the batteries and checking for voltage between the post and the cable. Watch out for additional lights added to the rear compartment. Contact Trucks didn't come with any, and mechanics being mechanics usually add some.
The only "flaw" that I know of (w/M1031's) is the cluster of a harness that runs on the driver's side frame rail. About under the drivers butt, the wire sometimes get fried by the exhaust pipe. Check here FIRST. Alot of highway time really heats up the pipes . /forums/images/icons/wink.gif