I am trying to determine which differential is in my 2007 2500HD. This is a 2wd (I really think it is a one wheel drive). Local Chevy dealer says it is a limited slip but I am sure it isn"t. VIN is 1GCHC29697EXXXXXX.

 

Look in the glove box. There should be a list of RPO codes. Prolly start with a G. Mine is GT5 for 4.10s. G80 would mean you have posi.
I used to be able light up both rear tires on my 07 2500HD, it's getting more and more difficult to do on pavement.

 

I've checked the codes in the glove box. There is a "GMC" & "GT4." The ratio is 3:73 (all diesels have this ratio). With 430hp, it will lite up "one" tire forever. I am guessing that the "GT4" is the actual rear end. It is a 14 bolt unit.

 

14bolt is the actual rearend, GT4 is just the gears it happens to have. I can light up one wheel all day, I used to be able to light up both forever. Wish I had me a Dmax.

 

Is there anyway to determine (using the build codes) if this is a limited slip or one wheel drive unit? I know what the bolt pattern is (14 bolt) and the ratio. If the unit is supposed to be a limited slip and is not functioning properly, I can have Chevy replace it. If it is actually built as a one wheel drive, I am going to have to replace the guts with an after market posi (I'm getting tired of getting stuck on wet grass).

Update: I've found the information. All RPO codes are listed at "www.rpocodes.com".

Many thanks for all the help. According to my build codes, I do not have a limited slip. I guess its time to buy the after market kit. Thanks again - Smitty