2007 Chevy 3500 gear ratio programming

Mar 30, 2016
Northern Michigan
2007 Chevy 3500 classic 6.0l/4l80e 4x4
Recently bought this truck knowing it had issues. It had been sitting for a while before I bought it. It had a misfire and torque converter did not lock up. I was hoping the misfire was causing the TC issue but it wasn't. Ended up doing a tune up and crank relearn which fixed the misfire. The TC issue ended up being the clutch lining in the TC went. So took care of that and finally got it locking up. That's when I realized the rpms were really low while driving down the highway. I've had and still have other trucks like this so I know about how they drive. Turns out someone swapped 3.42 gears in both axles and reprogrammed the ecm to correct for the gear change. So I swapped 4.10 axles back in and need to program the ecm back to the stock 4.10 ratio. I bought a super chips flascal calibrator to correct this but it won't let me proceed to do the gear change because it's says "calibration files not stock" which I knew they weren't stock. What I would like to know is since I'm putting this truck back to what it came from at the factory, can I just take it to the dealership and have the put a stock program in the ECM. I'd rather just have the dealership do it than deal with an aftermarket calibrator.
Possibly but the dealer might really not want to do this, make it expensive, make you buy a computer too, etc.

Seems like a question better answered by calling your dealer.
Don't tell the dealer that the PCM has been tuned, It will only serve to confuse them & not want to reprogram the PCM. And some dealers/techs won't reprogram modules unless it's part of a Campaign/Bulletin.....But will more than happy to Replace & Program a module.

There's a good chance that GM SPS can overwrite the PCM even if it's been "Locked" with HP-Tuners or EFI-Live. But there is a small chance the flash will fail if it's been "Locked".
If the PCM isn't original to the truck & has a different Operating System, Things can go sideways & at worse can "Brick" the PCM.

I specialize in GM Generation 3 LSx (P01 & P59) Controllers, If you want to ship your PCM to me.....I'm confident that I can get this squared away for you. PM me for pricing.