First, welcome to TDR.
Second, I inst. a set on my 06 2500 (see sig. below) and I'm sure your 08 is the same.
Do a search on this sight, there is a lot of info. and discussion on these units. Some love, some hate. I love.
I got a solid 1MPG increase, but what I really like is not spinning all the stuff in front of the transfer case, while driving down the road in 2WD. Also they have new wide spaced, serviceable wheel bearings, as opposed to the failure prone, non-serviceable, expensive, POS stock bearing packs.
Like I said, do a search and you'll probably get "more" info than you need.
Good Luck, Ray