It's Your Carrier Bearing... McGaugh's Or Bell Tech Has A Relocater Kit For It.
IT'S DRIVE LINE VIBRATION the carrier bearing needs to be raised.
no big deal though.

 

Well I am putting in a 4* shim today, hopefully that'll do it.

1-pc drive shaft.

 

oh ext cab...damn guess i should've look at ur pic huh . good luck.

 

Well the 4* shims made a big difference. The vibrations are minimal and really only felt at WOT between 65 and 75mph. I might not even notice it now if i hadn't had my attention drawn to it.

What do you think? Is this ok to Dyno like that? Take it to a drive line / rear end specialist?

 

I would try to add a 2* in there till its ALL gone. A "little" vibration can turn into a BIG one when the d-shaft is spinning at 6200rpm like it does on the dyno. Get it PERFECT before you try any high speed runs. Atleast me personally I wouldnt take the chance of killing someone when the shaft comes apart on the dyno or killing my brand new FLT trans or fuel tank. I would take care of your problem before I moved on to anything else.

 

I'll make a few calls Monday i guess.
Can i add a 2* shim to the 4*'s or do I just get 6*'s?
Oh, the stress. I get the bed lined Monday morning, then back to paint Mon evening for a day or two.
I hope i can get this thing dialed in before next Mon!

 

one thing at a time grasshopper.

 

O yes massta, grasshoppa get ahead of front wheel and squish head

 

What do you think? Is this ok to Dyno like that? Take it to a drive line / rear end specialist?[/QUOTE]

This isn't rocket science and it's not a guessing game either. Open the link I pasted earlier and it shows how to check and correct pinion angle. You have to check it sitting on the tires at normal weight.
The idea is to have the faces of the yolks parallel under acceleration. This is where the u-joints have to do the least amount of work.

 

Well my truck is going in Monday next week to swap in the FLT and I talked to Rick about checking the pinion angle. He wasn't overly concerned so i'll relax a bit.

Thanks.