So I've replaced my u-joints and center support bearing (both of which needed to be replaced, no doubt) but still have major vibrations at speed in my truck (2003 F-250 5.4 CCSB.) It only starts at about 50-55 MPH and again at 70 MPH or so, under acceleration ONLY. Taking my foot off the pedal takes the problem away. Crusing is fine. I've crossed driveshaft phasing out of the question as there's only one way my driveshaft could possibly go in, and I know I put the initial piece in correctly so everything else followed. U-joints are greased as well as the slip yoke. I've put the rear axle in the air on jack stands and had a friend get the speed up to 50 MPH, and again at 60 MPH, but I wasn't able to visibly notice or hear any vibrations or anything else being off.

I've been doing some research and started measuring my driveshaft angles. I have a two piece driveshaft with single cardan joints. Here are my measurements:

• Transfer Case Pinion: 6° down
• Output Shaft (From Transfer Case to Carrier Bearing): 4° down
• Slip Yoke Connector (on the Output Shaft): 5° down
• Driveshaft (From Carrier Bearing to Rear Axle): 6.5° down
• Rear Axle Pinion: 4° down

This makes my u-joint working angles:

• 2.0° at Transfer Case Pinion
• 2.5° at Slip Yoke
• 2.5° at Rear Axle

According to this link there are multiple ways for the angles to cancel out. However this is where I have reached my limit and need to reach out for help, lol. I know I need the transfer case pinion to be at or lower than 0.5° but I'm not sure how to get there.

Or, I could have looked at this whole thing wrong! I'm not sure, that's why I would like to request the help of you lovely folks

Oh and before I forget - the truck doesn't have a lift that I know of, as in I did not put a lift on. It looks like it's at stock ride height anyways, but leveled out. The carrier bearing is also at stock position, no shims.

 

Are your u-joints clocked correctly. I think those angles sound good. I am not a mechanic but have built lifted jeeps.

 

If you have a slip yoke shaft, then make sure the U joints at each end are true.
I had a drive shaft that I got 1 tooth off when I out it back together. It looked like the U joints were aligned, until I layed it out on the flat garage floor and could see they were barely out

 

I initially didn't respond 'cause your angles are a bit confusing....I always just measure directly on a u-joint cup, with that cup positioned horizontally you can take a socket to extend the "plane" of the cup and then measure off the base of the socket with a small angle finder. BUT....there's more than one way to skin a cat

Anyway I don't think a half degree is gonna matter at all. If you're getting noise on acceleration then something is moving... usually I suspect axle wrap which brings your pinion up and this is typically why you want your pinion angle maybe a couple degrees less than ideal because it will move to "ideal" under load.

For giggles if you're ever near a '95-04 Taco at a stoplight take a look at how much the axle rolls when they start from a dead stop. Of course SuperDuty spring packs are stiffer (we hope) but we're also making more torque and a lot of us have factory installed blocks.

The other possibility is carrier bearing or trans mount play allowing for angles to change under acceleration.