when i get onto the freeway and accelerate upto speed i have a pulsing vibration, feels like its right under my feet, and does not go away. it pulses for like a second or two then goes away for two to three seconds then comes back again...any ideas?

 

could be the fuel filter needs changed....
does it go away when you slow down a little???

 

Check below sounds like the same problem...

https://www.dieseltruckresource.com/...9-t221847.html

http://www.cumminsforum.com/forum/3r...ind-money.html

 

thanks for the links, it feels like its coming from the t-case/right under my feet but will try to find it by trial and error