I was never told how they adjusted the heat shields, I would look for areas where the shields contact each other and try an adjustment to space them better, if possible. In my case the heat shields would rub going over bumps or braking - but intermittently!Thank you very much for this - any hint is greatly appreciated, and your special expertise is clearly unrivaled. It is a petrol Quartermaster, should it make a difference. At its face, the whole underbody is very well designed and flawlessly executed, including heat shields. Will get under the truck tomorrow and look at the shields closer - to this end, what exactly do you mean by „adjusted“ if I may?