HELP !!
 

alright guys i have 03 cummins now i have virbrason when hit about 68 mph and goes away at 70 mph not sure what it was but i like to kinda know, so to start off i just re build the trans. did the trans mount both front and rear drive shafts, done both front hubs and everything else is tight as drum in the front end and i thought it was tires so i did those they were worn down due to be done any way so i put Cooper A/T 3's on and Still have the virbrasion any ideas ? any one else have this issue ??? truck is stock has 120,000 miles has 4:10's in the rear endand it's a 4x4

Sounds like a simple tire balance problem! Also check your shocks! Whenever it's at a specific speed and goes away it's a balance issue!

thanks will try that i just put brand new Cooper A/T 3 on the truck so i think the tires should be good but i know i put rear shocks in the truck once maybe? and the fronts have never been done so it might be the issue so try changing them and go from there ! thats for the help !

It can also be a loose u joint or bad carrier bearing... They will cause vibration too to check you carrier bearing drive it around the block once or twice and see how hot your carrier bearing is if its extreamly hot its bad.. If not your ok. U - Joints is a simple mater of checking play in them.. But it can also be tires.

Same problem here

^ so it's not just me that has this problem and if remeber right i've done the carrier bearing when i did the drive shafts