i,m not really new to this forum, i've moved and changed my user name. a keen observer may figure out who i used to be. i'm about to go out of warranty and have discovered an inconsistent shudder. shake, or vibration at 2 different speeds. one time it occured on a road i frequently travel between 30 and 40 mph. the whole truck shook! i was just a mile from my house so i shrugged my shoulders and thought maybe it was the wind since it was quite windy. then just 15 miles remaining of a370 mile trip home, for a 4 mile stretch at 75 mph it did it again. then as fast as it came, it went away! i have a few mods including: 5 lb pulley, factory tech trans kit, jlp chip, and cone filter. i couldn't find a similar problem regarding the 2 different speeds so that's why i need help. thanks,
john

 

I think Ford may have a fix for the low speed vibration. The high speed vibration probably has to do with the muffler. Several of us have changed out the cat back and lost the vibration.

 

so, you think it is 2 different problems? what is the low speed fix?

 

What does the VT stand for? Vermont?

 

yep. moved from delaware a little over a year ago. love the outdoors, but i can't keep the truck clean!