Yep, I have the same issue on mine. Although mine is a 4x2. Still haven't reached 3k miles yet but the shudder has been with me since day 1. Too lazy to take it back to the dealer. [emoji51]
I took the Sam Adams Brewery tour and at the end you get a couple of their beers to taste. We had Cold Snap from tap, OMG the difference in taste from the ones sold in a can is big!
I installed mine yesterday and it's actually 5 bolts. You need a 12 socket to take the factory bolts and a 13 to put the new ones in. Check out this video: http://youtu.be/XWpOSzNGRh4
It all depends what you want out of it. In my case, the FJ is the household offroad vehicle. The SR5 will mainly be street driven with occasional mild dirt or gravel trails so no need for 4x4 or lockers or crawl controls, etc. I'll just put some A/T tires for better traction in case said trails...