I have a 2002 silverado crew 4wd ling bed diesel Vin 1GCHK23172F206168. This is my first winter that I have to spend the entire winter up here in the Colorado mountains. I purchased it used many years ago and have always known that the Gov-lock doesn't work, but now it's an issue. I'm tired of having to winch myself up my driveway in the morning (and the Subi drivers laugh at me). The road scraper guy won't let me park up on the road so I have a problem. So I have to get a new limited slip. It's really cold up here and there's a lot of snow and I have to get to work every day, that makes it imperative that I get the correct unit the first time. I can't leave the truck stationary for a ling time. Got to get it correct the first time and get the old one out and the new one in in a short time.
No more Gov-locks. It seems that they have a poor reputation, but Chevy keeps making them. I've decided to get an Eaton Truetrack or other gear based limited slip. The problem is I can't find the definitive answer to exactly what differential the truck has other than what I can determine from looking at it from the outside. I have determined it is a 3.7 ratio. It's a 14 bold (I can count that high), but it seems that it could have a 10 or 11.25 inch ring gear and 30 or 31 spline axles. I've tried several VIN decoders (including the one for this forum) and none will tell exactly what diff the truck has.
Can any of the "true" Chevy Truck gurus here impart any knowledge to me of what is inside the rear end:
Thanks in advance for any help.

 

are you doing the work yourself? Setting up an axle isn't really a job for a beginner.
If you're taking to a shop, then they will identify the correct parts.
I'm on my second vehicle with a G80 govlock rear and no issues. Marvelous in the snow. They work fine if you don't drive it like a teenager.

https://www.sierragear.com/different...dentification/
https://www.rockauto.com/genImages/AxleID/axleDims.html
https://www.differentials.com/techni...dentification/
https://lugnut4x4.com/axles/14-bolt-...dentification/

 

By your VIN I see you have a 3/4 ton with a Duramax. You should have an 11.5". The 10.5 was used behind the 6.0L gasser and the pinion gear is removable from the front. The 11.5 is not. As for the axle splines, you can slide an axle out and count the splines. Just remember to get a gasket or some use sealer and top off the diff when you put it back in.

 

Well, this truck was used primarily (until recently) for towing. I purchased from a race buddy who towed a big gooseneck. I tow my Sunbeam tiger in an 18 footer. It had a dead govlock when I purchased it but as long as I kept it in California I didn't have any issues. Now I'm in the Colorado mountains and have a steep driveway and lots of snow. I had planed to change it myself but have been thinking better of that. The problem is that I have to do the transaction in one time and can't risk the unit not fitting when the dif is disassembled so I'm trying to determine the exact unit so the change can be done in one day. So I've been surfing the chevy forums hoping to find the exact correct replacement.
Thanks for the response and I'll follow your links.

 

Thanks, you got it. It's very cold and snowy here in Kremmling Colorado, I have really crappy work hours, and I was trying to not have to go out in the cold and snow with a flash light to pull an axle. I've made a deal with the "Differential Guy" (business name in Colorado Springs) to let me use my discount at Summit racing to get the replacement, but he only wants my truck on his rack for one day and it's 380 mile round trip so I also want to be able to have the truck back in one day.