Just wanted to make a quick post on my results after going with 4.88 gears. There is so much info out there, it was not a easy decision to make and pricey. Lots of charts, graphs and opinions. Even the guys at the shop were a bit scared of going with 4.88s My specs '09 auto BFG 305/70r/16 (had 3.73) only 23500 miles it's not a DD Ended up paying about $2200 total and got a extra 3/35000 mile warranty, done at 4wd parts. In 4th gear with the TC locked: 65 mph I'm at just over 2100 rpm 70 mph 2300 rpm It does accelerate a bit smoother, it feels like you are getting more power as the rpms climb. Rpms rise the speedo at least moves. I haven't got on it hard, waiting to break them in a bit. It's not a miracle and for $2200 it may not be for everyone, but, after driving around so long with the 3.73 it's a true improvement. Since I plan on keeping this rig until it doesn't run anymore I think it was a good investment.