Check the u-joint straps, too, Eric. Grab firmly ahold of that front shaft and try to shake the crap out of it. It should be rock solid. If you remove the front shaft for new joints, balancing, etc. make sure you buy new a new strap and bolt kit for $6. Don't reuse the old ones even if they look good. They are designed to stretch and clamp ONCE and are dirt cheap compared to yokes and u-joints.
If you need new outer axle joints, replace the $3 PLASTIC bushing in the end of the outer passenger side shaft where it mates to the inner shaft at the CAD. There is a good chance, with any vibration on the outer u-joints, ball joints, etc. , that your inner axle seal, especially the passenger side, is worn and leaking, too. Even a slightly loose or wobbly axle shaft will egg it out in a hurry.
I highly recommend nothing but Genuine Spicer replacement parts. They cost no more and fit right. And except for maybe those CMT $300-apiece super u-joints, I honestly don't think anyone makes as good a u-joint as Spicer. Sadlers, the local axle and driveline shop here in Cedar Rapids, uses nothing but Spicer components. Their prices for Spicer u-joints, installed onto my carry-in shafts, was less than Napa's do-it-yourself price for their premium joints. If you have an expert driveline shop like Sadlers in Des Moines, letting them inspect and rebuild your front driveshaft is a good idea. The shop foreman here is great at spotting and pointing out things I might miss. He knew I had strap issues at a glance, and that they were caused by reusing the straps and bolts when my 5th gear nut was fixed (look for shiny spots on your caps where they are turning or moving in the yoke and straps).
The thing about frontend shaking and vibrations, like a bad u-joint, is that they will start causing other components to fail in short order if not addressed right away. I have a huge stack of new parts receipts, and an even bigger stack of trashed front tires, to prove how expensive it can get.
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