I just looked up the RPO codes for my 99 Sierra exc cab and found out I had 3.08 gears. Damn. Good for gas not good for drag racing. At 70mph I'm at 1700 RPM does that sound about right? What do you think my top speed would be? How much do you think I would pick up with 4.10's?

 

3.08, damn I thought my 3.42's were bad, at 70 mph I'm at about 2000rpms or so. I think you'd see some pretty good gains from a swap to 4.10's

 

most definetly get some 4.10 gears. your mileage will change one or 2 miles a gallon but that's about it.

 

Wow I'd figure there'd be a bigger difference in RPMs from a 3.08 to 3.73 gears. I have 3.73 and run right around 2K at 70mph.

 

At 70mph I'm at 2500rpm......with 31.9" tall tires, 4.10's and an 80e (.75:1 4th gear instead of the .70:1 in the 60e)

 

My gas mileage isn't even all that great. I get around 16-17 normally with a balance of city and highway. On trips though it gets really good nearly 20. With 4.10 it would be a lot better. I was pretty bummed when I found out about 3.08 though. At least there is power to unlock. How much are say eation posi 4.10's?

 

how do you know what gears ya got?

 

Look up the RPO codes on the net. They are found in your glove box what the diffrent codes are. Every option in your truck has a diffrent code.

 

yeah 3.08's must suck, but good on gas. I just put 4.10's in my truck and i am around 2500 rpms at 80mph. i went from 3.42 to 4.10 and it really gave me alot of torque and made the truck pull alot harder it feels like.

 

Our ESCALADE has 4.10's I believe and it goes through the gears a lot faster than my truck. My trucks gears are long. My job requires a lot of stop and go driving which isn't the best on 3.08's. How much is a good 4.10 set up?