I could use a little help identifying my rear axle and diff. All I know is that it has 14 bolts on the rear cover, big ribs around the front side and a vent tube that goes to the left side rail. Perhaps the 1-ton configuration helps.

Thank you.

 

BTW, the sales sticker said it had a locking differential-rear axle.

 

Have you looked inside the glove box at the RPO code sticker? The 3 digit codes that start with G are for the rear end. For example, my 1996 C1500 has "GU6" which decodes as a 3.42 ratio rear axle, WITHOUT locking. My 2006 Silverado has two of the G codes - GU5 for a 3.23 rear axle ratio, and G80 for the automatic locking rear differential.

I expect you have G80 as that is the code for the automatic locking rear end, and a second code for the axle ratio, just like on my Silverado.

Codes can be decoded at https://decoderpo.com

 

Thank you very much, I tend to agree with you and was leaning that way based on other things I read and pictures I saw. I believe mine is the second generation of the style because if it a huge pumpkin with big ribs on the front side. Evidently the first gen did not have that form.

 

I meant to mention that the door sticker is all bleached out, and the two stickers in the floor of the glove box are similarly unreadable. I have not been able to find replacements for mine because it appears to be too new.

 

Ok - there is a VIN decoder that may be able to assist you. It is right here, on the Tools menu at the top of the page. Just click on Tools->VIN Decoder. Put your VIN in there and see if it can tell you what the original equipment was. Let me know what you find out.

 

{GT4} 3.73 rear axle ratio

 

Glad you found it!

If you still have the owners manual, that axle ratio along with the engine and other info should tell you the max towing capacity. For the GMT400, in my 1996 owners manual, it mentions that the max towing capacity can only be achieved with an optional engine oil cooler. Which my truck does not have - I just have the standard transmission cooler. I've never towed anything bigger than a boat though - maybe 2000 pounds with a bumper mounted ball hitch. If I tow anything these days I will use my 2006 Silverado with a receiver hitch.

 

The bottom line is that the sales receipt and the look of the unit appears to be G80 locking.

 

That makes sense. They pretty much used the G80 on all the heavier duty 90's trucks. My 2006 has it due to being a WT (Work truck) trim level and having towing packages.