I have an 04 duallly with a 410 rear end . At 65-70 mph it has a slight vibration you can feel in the seat, its almost like a hum. I was wondering if anyone else notices this or is it normal?

 

Not normal for a brand new truck. How many miles on the tires?

 

Have you checked the rearend fluid level? Alot of them came 1 to 2 qts low from the factory

 

Man, I had that problem in my 98. Mine started @ about 37K and the hum started to get louder. Then @ about 38.5K it started to whine a bit. Well, found it to be pitted bearings. $900 later, the hum and whine was gone. I wish I had the 7/70 then.

That was my experience, hope it aint yours...

 

Make sure yours has the UPDATED powersteering hose with the C weight before you chase rear axel problems.The OLD hose causes vibration and noise at the speed you indicate.Try it at the same RPM range in neutral and see if its still there.