I just did a 3.42 to 4.10 swap on my '05 4x4... to be exact, I had it done at performance shop using Motive gears which I got online at very good price; gears are dead quiet. Took them through recommended break-in procedure and used synth lube in diffs. Personally, this is one area of repair I stay away from as I'm not wanting to ruin a large investment.

The local GMC dealer whom I'm on good terms with would overlook lots of stuff I did, but said if they knew I had swapped gears, they'd void my entire driveline warranty. They had originally said they'd do the swap but then changed their minds so I looked elsewhere. It all stinks since 4.10's are an option on shortbed reg cab 4x4's. GM has ticked my off mightily in recent years; I've only bought about 25 cars (mostly Chevy) from them!!!