6” Rough Country lift.
And I used the Extended travel CV axles from NAPA to give me a more flexibility. The 2008 axles are 1/2” shorter than the total length of the factory 2004 axles + the 2” CV spacer from Rough Country. So if you use the ‘08 axles and go to full droop (especially with aftermarket UCAs) you may pull the conventional CV axles apart and cause a failure. Better to add the extended travel CV axles to cover the missing 1/2” and give you another inch or so of travel before failure. Of course this is if you use the truck off road…if it’s just for the look you should be fine without the extended travel.
They are pricey but worth I think.
FYI for everyone interested in the Extended travel CV axle...if you look on the warranty sheet on NAPA's website you will find a phone number...google that number and you will see the manufacturer of the axle is Trakmotive...the Trakmotive axle on Rockauto for the 2008 Tahoe sells for $131...the one on NAPA sells for $330 ea...double the cost!!! I caught the Black Friday/Cyber Monday sale for mine but I still paid $250 ea.
I hope you can learn from my mistake. Best of luck to us all.