The driveshaft issue is is a toss up....might have to do something but you might not

You might want to check and see if they guys you're getting the lift from are going to include the rear shocks, extended brake lines and AAL. None of them are included in the basic kit and you need all of them. Your rear shocks aren't long enough to use with 8" of lift. All trucks from late 05 to 08 need the extended brake lines. The AAL is what bumps the rear up from the 6" the block gives to the 8" you need. If you don't get it, the rear will still be at 6".

4.88's are what you should run for 37's and up. They'll cost you about $1500 for parts and labor. You can get away with not regearing for awhile so long as you take it easy and you correct your speedo so that the tranny shifts when it is supposed to. The sooner you get gears, the better off you are though.

37's are NOT bigger than the wheel wells. You can safely tuck a 38 into the wells. Take a look at Texan Aviator's gallery pics and you'll see the proof.

 

The shop I am using just did one a month back and my quote included brake extentions and aal. I may save up and see if they will cut a deal on the gear install while I am up there. Might as well get it all done at once.

 

It'll save you money to do the gears at the same time as the lift becuse the front differential will already be out from the lift install. You'll save on the labor costs to take the diff out.