I have a rough chatter noise coming from the rear end. It happens when starting off up till about 25mph. It rattles the cab a little and sounds real rough. It also happens when turning up hill, causes lots of vibrations in the cab. Some have mentioned it could be the rear differential needing a friction modifier or the u-joints needs some special lube? Any input? Its an 05 F150 with 62K miles.

 

U-joint on the camshaft? WTF is that?

Check the u-joints on the driveshaft. If they are tight, try a bottle of Ford friction modifier - assuming you have a limited slip diff.

 

I meant drive shaft my bad. How do I tell if the u-joints are tight?

 

Get under the truck, twist and shake the driveshaft and watch them.

 

When I first purchased my truck last year I was experiencing chatter when making sharp turns and accelerating. Turned out that my pinion seal on the rear diff was shot and I was down over a quart of fluid. Replaced the seal and put a good synthetic in and the chatter went away. If you don't see a leak (driveshaft near the diff will be wet, and the underside of the truck right above will probably be covered in oil from being flung by the driveshaft) then your fluid is probably shot. Good luck.

 

Just took my 08 with 45k on it in for the same thing. There is an updated clutch pack for the limited slip. Mine is under warranty so there's no charge. Oddly it started happening after they replaced the input seal on the rear diff because it was leaking.