Cost for re-gearing? 3.08 to 3.42

Gasser43 · November 25, 2017

Hey guys,

Couple months ago I purchased a Silverado z71 crew cab 4x4. It was a 2015 used and when checking vin lookups as the window sticker was not available, they said 3.42 gearing. Now I've asked the dealer to email me an RPO for the truck and it shows 3.08!! I'm really bummed as I bought it thinking it was 3.42 gears which puts the towing capacity at 9200 vs 6400 lbs. I'm wanting to tow a travel trailer about 7000 lbs. Anyone know how much it would be to replace the front and rear to 3.42 gearing?

Thank you for your time!

6.2Chevy · November 25, 2017

Is the RPO the only way to find the end gear ratio?

O_J_Simpson · November 26, 2017

39 minutes ago, 6.2Chevy said:

Is the RPO the only way to find the end gear ratio?

You can always craw under the truck and check.

Gasser43 · November 26, 2017

I tried crawling under it and looked all over with no luck to find the ratio stamped on the rear diff. Also, I found in the glove box the gearing code that does state it is 3.08 unfortunately. Really let down with GM selling a 1/2 ton 4x4 with a hitch AND an electronic brake controller with 3.08 gears.

2017HD · November 26, 2017

I did this to an S-10 back in 83 - by the time I was finished with the rear only (it was 2WD) I had just over $500.00 into it. A lot depends on how much you need to change - I did not have to change anything other than the ring and pinion gears plus all the seals and bearings in the rear end. My dealer also misrepresented the towing capacity of my truck - he quoted me the 3.73 rear gear towing - not the 3.08 - this was my learning lesson on tow ratings.

Back then I also had to change the speedometer drive gear in the transmission. Today you would need to have the control module re-flashed. I would also shop around- I got the best deal at a GMC dealer for both parts and labor.

swathdiver · November 26, 2017

The codes (different) should be on the axle tube as well. I would ask the fella that told you 3.42 how he knows, maybe someone already switched them out.

Gasser43 · November 26, 2017

Thanks guys, I'll check on the axle tube for a code and ask the dealer to verify this.

Silverado4x4 · November 26, 2017

10 hours ago, Gasser43 said:

Thanks guys, I'll check on the axle tube for a code and ask the dealer to verify this.

If you cant find out what the gearing is jack both rear wheels off the ground mark the driveshaft turn the rear wheel by hand 1 complete turn and count how many times the driveshaft spins, if it spins 3 times then its a 3.08, spins almost 3.5 times then its a 3.42, spins 3.75 times then its a 3.73 and so on.