Has anybody changed the rear end gearing in a current generation express?
I have a ’24 3500 extended with the 6.6 and the 6L90. It has about 50k on it now and I really want to change out the rear end for a 4.10 instead of the 3.42.
All 50k has been pulling a very oversized load weighing in at 10k. It would be great to get the rpms up and use more than 4 gears. That is the only thing this van is used for. It tows 100% of the time.
Before I order the ring and pinion set, has anybody attempted to have the ECM/TCM reprogrammed with a different ratio?
I know it was easy enough with the old 6.0 but not 100% with the new ones.

 

With towing so much have you thought about swapping in a 10.5" 14-bolt full floater? Your '24 still has a 9.5" 14-bolt semi floating axle? Do you have a press for the pinion bearing shims?

I've done a ring and pinion on a 10.5 before, and put a limited slip in the 9.5 in my '15 3500 so I know a bit on the topic. The Duramax vans I believe came with a 10.5 which wasn't hard to do the R&P on because of the removable pinion housing and the adjusters for backlash. Crushing the crush sleeve just right was hard though. Might be easier with an impact like my new Harbor Freight ultra torque. I did it with a pipe on a breaker bar and over crushed the first 2.

You are also going to need to get the speedometer reprogrammed. I think you will have to go to the dealership for that.

FYI this is what a 9.5" looks like

 

I am kind of in a similar place.

I have a 2016 with 6.0, so it has the 9.5" with 3.42 ratio. The rear end has a pronounced pinion whine. Bought used, only 62k miles, maybe it was improperly installed from the factory. (crush sleeve you mention, shims, etc.) So it needs to be taken apart and rebuilt. I tow a lot so this presents an opportunity to regear to 4.10 along the way.

Although I'd love to get a junkyard 10.5, rebuild it, swap for a truetrac, regear, and then swap onto the van, this would take skills, tools, time, and money I don't have at the moment. So I put that idea on a shelf for a future project in a couple years.

East Coast Gear Supply is fairly local for me and axles/diffs/drivelines is all they do - so I'm taking it there on Friday. But they won't reprogram the speedometer, so I'm trying to figure my options for that. Could take it to a dealer, find a specialty shop that can do tuning like this, or get a tuner and do it myself.

 

Maybe start here. Sounds like people had little luck at the dealership. Maybe they could help for what was a factory option?
https://chevroletforum.com/forum/exp...ration-109112/