I'm looking to get a crew cab standard bed 4x as a DD and to tow the K5 every so often. Looking at 01 and 02, trying to stay below $20K. Anyway the 1500HD looks to be rated only about 600 lbs less GVW than the 2500HD. A dealer told me the difference is in the body-- the hood and clearance for the ally tranny or something like that. Is that true or are there more substantial differences other than just engine/tranny choices?