I'm considering the purchase of a new 07 GMC Sierra 1500 4x4. There is a nice truck on the lot at my local dealership that meets my towing needs (5.3L V8, tow pkg, etc). However, the rear axle ratio is 3.43 (I don't understand how it could have the towing pkg & have this axle ratio).

My current GMC has a 5.7L V8 with a 3.73 rear axle.
I have a travel trailer in the 6,000-7,000 lb class.

Is it advisable or possible to have the dealer switch out the rear axle gears for a 3.73 or 4.10 set?

Thanks,

Jeff    

We're told it's not that unusual for quite a few half-ton truck buyers to get the short gear ratios because of how much they drive on the highway and around town without thier trailer. Regardless, if you're at all interested in keeping the rpms in the strongest part of the powerband, you should probably swap in a set of 3.73:1 gears. And if you spend a lot of time pulling near max loads, you might want to bump up to 4.10s. However, understand with each jump in axle ratios, you'll still be dealing with the same 4-speed tranny they've had for years. Your average and empty fuel economy will suffer. If, for some reason, your local dealership isn't comfortable swapping ring and pinions into your truck, track down a good 4x4 shop and know how to make it happen. Of note: there is some computer changes that will have to be addressed when swapping ratios to keep all the braking and gauges reading correctly. Good luck.