I have a mystery on my hands. I thought about it today thats why I bring it up. Last summer I'm driving down the freeway about 65-70 mph pulling about 7K on a trailer in overdrive. I should've not been driving that fast with a load , but oh well. Anyway, I heard a loud boom similar to a tire blowing out. It was so loud and powerfull that I felt it in the cab. I felt the vibration in the steering wheel. It scared the crap out of me so I pulled over and first checked my pants then my truck and trailer. I found no blown tires and the truck was still running. I got back on the freeway and noticed that I lost a bit of power. So I dropped my load and went to the dodge dealer, but they couldn't find nothing. So, I went to the cummins dealer, hooked it up to diagnostics and nothing. By the way, my truck was pretty much stock( 98. 5 24v with an automatic 45k)at the time except for a 4" cat back and a free flow air filter. They strapted it on the dyno and it was puting out 160 rwhp. It seemed kinda low so the tech. changed the fuel filter and picked up another 20hp. Anyway they couldn't find nothing wrong with the truck, the after cooler looked fine with no busted connections. Its been almost a year and the truck runs fine. Just thought I'd throw that at ya guys, maybe someone knows whats up or had a similar experience. Thanks.