I have an 03 2500 with the 5.7 Hemi, I purchased it from an older couple after sitting for over a year on grass so needless to say the under carriage has lots of rust, but I got it for a really good price, almost free. The problem that I am having is when I'm driving down the highway I get a terrible vibration (almost scary) but the weird thing about it is that it's not constant, it will shake for about 20 seconds and then it will be real smooth for about a minute and then it comes back again. I'm not thinking it's the rims or tires because I would think it would do it all the time. I'm wondering if maybe it could be the front axles or possibly the driveshaft. I'm hoping someone can help me out because it drives me crazy. I don't drive on the highway often but when I do I always wonder if something is going to fall off.