What gears to run? Help, I'm not keen

[Big_Olde_SD]

Well guys, I've been busy putting together my new set of tires for the SD. I'm going from my 325/60/20s to so good old 37x13.50x18s. So the issue regarding a gear job has been brought up. The truck is stock as far as I know. Throughout my readings I came up with two choices some 4.30s or 4.56s. I don't tow much, and care about the performance of the truck and its gas milage. Its a 99 4WD with the V10. I'm currently getting about 12-14 on a good day on the highway. Also to have someone install them what would be a rough number to expect to pay for in labor? Any help would be greatly appreciated. Thanks again this forum rocks!

[blackout]

I was quoted a grand to install used 3.55s front and back, that included the gears.

[lubbockguy1979]

i would expect to pay between 250-500 in labor per axle. i am pretty sure you can go to randy's ring and pinion and they have a gear calculator that should give you an idea of what your rpm range will be with your final drive ratio. one thing to think about is if you are lifting your truck you will have more potential for wind drag and weight both from lift components and the sheer weight of the aftermarket wheels and tires. if i were to lift my truck i would choose at least a 4.56 if not something closer to a 4.88 or 5.13 for tires 37" or larger. if i was planning on staying around 35" i would ideally choose the 4.30. lower gears are generally always prefered if you are planning on regearing because they make the truck seem more peppy and make the lift and tires less noticable. with the right gears a lifted truck (with larger tires) will run and have similar acceleration to a stock truck. the milage should also improve on the highway... city milage might not change to much

[Heavy_Metal]

Use 4.56. It makes a final ratio of claser to 4.20 which is perfect for the '99 V10. You may want to look into a blower after that though.