I have been putting off a long trip because I have a pretty good vibration from about 60 to 72. I have tried everything and cannot get rid of it, I have replaced:
Ball joints
drag link
wheel bearings
u joints
carrier bearing
front tires
spline on rear driveshaft

-drive shaft balanced (twice)
-front end aligned
-wheels balanced
-wheels checked for runout

It feels like its coming from the driveshaft, but its been gone all through twice. Everything is tight everywhere, I just shimmed carrier bearing to get all driveshaft angles to about 2 degrees.
After all this it still vibrates! It has gotten better, but still not acceptable.

The only thing left I can think of is the tailshaft bushing in the trans?? I can move it a little (I mean very little) up and down...is there a puller/driver available to change that in the truck??

Please help, I need to head back to see family ASAP.

Thanks.

 

Does it change with engine speed? Shifting down, does it change or not?

 

60 to 72 MPH is typical vib range for tires. Is this a drumming vib or shaking of stomach. A drive line vib is really irritating to say the least. Looks as have been through drive line system. Is it possible the center bearing is out of position (right or Left of straight)......
Like someone asked, what happens in neutral (say coasting down hill) or in direct at same speed.
Does it change when bed is heavy loaded? Are you running 80 PSI in tires?

 

Does not change with engine speed, only ground speed.
Tires have been balanced, and I have Centramatics installed.
This is a see nothing out the mirrors shaking, like riding a out of balance washing machine.
Center bearing is as straight as can be.
Direct/OD no difference.
Tires all at 80PSI

 

Have you inspected the tires for a seperation? Lots of shops will balance a tire without noticing, or caring. No matter how many times you balance it, you won't lose the run out.

 

did u change ure trac-bar?? if not i would check that!! best thing i ever did!! $128 bucks with lifetime warrenty and free replacement!!

 

I don't know what you meann by tire separation?

I don't have a track bar...its a 2wd A frame suspension, and its all new front is as good as new.

Ughhhh! I am out of ideas!!

I can only see a little play in the trans bushing, thats all I can find....Does anyone know how to change that?

 

Trans bushing? Where at?
I have similar vibe and I have play in the yoke that slips into the back of transmission, the piece with the big rubber doughnut. Im going to try that next.

 

Yeah....the slip yoke bushing in the tailhousing...same as you are talking about...I can move the yoke up and down about .020 by hand.
I just called a tranny shop...they said $150.00 to replace it, so I guess they don't have to yank the trans.