Stock gearing??? 05 1500 5.3 4x4

Red Clay · December 8, 2013

I'm wondering if this sounds like stock gear to those who may know.

@ 65mph I turn roughly 1800 rpm in od if I press just a little on the gas to get it to drop down I turn right at 2000rpm. I have 33 inch tires on her.

It reacts the same in both 2wd and 4hi. Any thoughts at to what gears I'm running. I know I can go crawl under the rear axle and look for a tag but that tag doesn't mean po didn't replace gears and leave the tag. Besides there is a good bit of snow on the ground here and I don't wanna crawl under her unless I gotta lol.

I just want to see where I'm at before I start thinking of regearing.

mstevens · December 8, 2013

have you looked for the diff gearing code in the glovebox? probably stock 3.73

kstruckcountry · December 8, 2013

I have 3.73's and spin about the same RPM. 2000 at 70.

govener71 · December 9, 2013

I have 3.42's and am around 1600 at 70. 3.73 sounds right then. If it's a z71 extended cab there's a good chance.

Mckenzie · December 9, 2013

3.73's more than likely!

Red Clay · December 9, 2013

I found this chart are 4lo.com. And according to it I'm not even on it with 33 inch tires. It's says with 33s going 65 at 2191 rpm Id have 3.31 gearing. And at 3.73 I'd be turning 2469 roughly. So I guess this chart is crap.

So what is the formula I would use to determine how going to lower gears would effect my hwy mileage. I was thinking of going to 35s with gearing between 4.10-4.56. But I don't wanna go too low.

But now I'm thinking of just throwing the 35s on and seeing how she reacts. Any body got any solid numbers for this gearing/tire combo?

Right now I'm getting about 16.1 city and 21.2 hwy.

and she is pretty much stock as far as performance mods. No cai looks like factory exhaust. Planning a 40 series delta flow 3-2.5(2) and a MIT. Maybe later a different cam as I just want more low end torq.