I have been battling a vibration for about 7k miles now. I have 65k on the truck and have a vibration at about 67mph. I replaced ball joints and every U-joint on the truck. I finally gave in and went to the ******* because I also heard a grouling or grinding during slowing down and the rear diff plug had a big gob a metal paste and a few shavings on it. Thinking it was a bearing.

It ended up that they told me without a doubt, it was my exhaust!!

I couldnt believe it, but it was really bad when I got it back, it even vibed at idle and variable other speeds. I made some adjustments to test the theory and the vibe got better. I added some hangers and stabilized it to just be around 67mph. But I still cant get rid of it.

Anyone have any helpful ideas or similar experiences to throw at me?

It is a homemade exhaust, but I never had the problem when I first put it together.