Running it in gear on jacks will not show anything, you need a load on the wheels, not just the axle hanging in the air, also the pinion angle is changed, the only way is a chassis dyno, in California all the shops that do emission testing have them, in your area I don't know, but without the load on the tires, and pinion angle the same as when it's being driven your not going to see anything.
In my case, no. I positioned the jacks under the axle tubes. Was not hanging, there was load on the suspension, and the pinion was at road angle.
In my case we had jack stands under the axles so no change in pinion angle etc.
Exactly.
Come the weekend I think we will continue to play. We have narrowed it down to the front axle. Process of thought is as follows:
Not driveshaft.
Not rear.
Not trans.
Not T case rear output.
Proof: all rebuilt or new from the t case back and still have it. Also can put only rear axle on stands and it runs smooth. Front side not turning. Next we look there.
Put front and rear on stands and it is there.
Not front driveshaft as we pulled it went for drive, vibation still there. This also elliminates t case as the front output was not turning as the prop shaft was out.
Not tires. Proof: We put back on jackstands and pull front rims tires off and put truck into 4wd and still there although not as noticiable. I say due to virtually no load on axle as tires are off. Still can be felt.
This leaves axle. U joints were replaced in the spring. Unlikely as they are premium greasable. Possible one bad one though.
Ball joints were done.
As the nature of it seems to be an up and down type of motion, and more noticable under load, I am leaning toward maybe front pinion. Ends of the axle were open due to the U joint change, so this area being untouched would be my first thought. Also symptoms seems right as do conditions.
Next step is to put back on stands and test this theory.
How much runout should be measurable taking a dial indicator off the front diff yoke?
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