I have meticulously maintained my one-owner '89 K5 from day one (161,000 miles on her now), but the rust really took off a few years ago. First, I had to replace the rear portion of the bed because the metal around the tailgate hinges had gotten to the point where there wasn't much holding the gate on. I just replaced the inner and outer fenders (the quarters are still okay), but I still need rocker panels and an outer tailgate skin (bottom rotted in the middle). The bottoms of the doors have gotten rough as well, and a curious hole has quickly formed next to the driver's side outside door handle, so both the doors will need to go eventually. What really kills me is the fact that I see plenty of '89-'91 Blazers and Suburbans in my area of the Northeastern US which are virtually rust-free, (some with quite obviously their original paint), and wonder why my truck in particular was so viciously attacked. Of course, it's been driven every day, yet hand-washed and waxed religiously. I took the advice of my owner's manual which stated, "No additional rustproofing is necessary". Could that be wrong? Would undercoating have made a difference?