Vibration

I have a vibration while slowing down. The vibration is between 43 and 47 mph. I am not using the brakes. The tires are match mounted and are perfectly balanced, and there are no bent wheels. What else could it be??

Check for loose u-joints.

what year is your truck?

it is a 2004 silverado z71. i had it at a shop today and checked all u-joints. they were tight. i was talking to a friend about it and he said somthing about "death wobble". i guess it has something to do with the caster numbers during an alignment. could that cause a problem like this or not?

It is possible. when was the last time it was in for an alignment?

Did you change the height front or rear of the truck like a lift kit or lowered the front end?

i just bought a set of tires a few weeks ago. along with the tires i had the alignment checked and they set it and gave me a print out. the numbers were within specs.

no i have not changed the ride height. as far as i know the factory height is still set.