I'm about to get a new Duramax 2500 Z71 LTZ. This will be my 3rd. I see that most of them are either 3.73 or 4.10 Ratios. I'm not sure what mine is, and the door edge sticker codes aren't clear. I'd like to get the same that I presently have. I typically am pulling my boat, but occasionally a 38' travel trailer, and a 20' trailer with a 75 hp Deere tractor. Will be pulling the travel trailer more as time goes on, but still most of the time just my brief case. I'd like to figure out what mine is. Can anybody tell what code indicates the gear ratio? I'm leaning towards a 3.73 for the better mileage. Thanks for your help.

http://www.crawlpedia.com/rpo_axle_codes.htm


To find the axle gear ratio of any GM vehicle, locate the RPO sticker (typically located in the glove box) and write down any codes starting with F, G, or H. Then, find those codes in the table below.

I don't believe GM has ever made a duramax with anything other than 3.73 gears. 4.10's are an option but when you select the duramax engine that option goes away and you get 3.73's as the only available offering.

Thanks for the link Samson. Looked it up, and mine is a 3.73 Red, 3 of the 8 2500 Duramax's at my local dealer are 4.10's. Might be an 18' thing. I'm going to stick with a 3.73. Unless you pulled a backhoe I can't imagine needing 4.10's. That 75 hp. Deere, or a 70 hp track skid steer are easy enough for mine with 3.73's.

Are you looking online? I bet its an error or typo.

Just looked on their website, with the duramax comes 3.73 gears only way it comes.

There's 3 18's at PArkway with 410's on the spec sheets. Maybe they special ordered them. I'm going 3.73's anyway

I just bought a Duramax it has the 373 gears would not get anything else. Had a 97 with 373 then a 2009 with a 342. The 373 ran circles around the 342 in all as specs.

GM doesn�t and has never produced the duramax with anything but 3.73�s. The duramax is an option. 4.1:1 gears will be listed as standard equipment and along with the duramax under optional will be 3.73�s.

Wish one of the gm dealers would respond lol none of them have 4.10�s

As far as I know, when you add the duramax option it switches from 4.10s to 3.73. Only the gas engine comes in 4.10s.

All you need is 3.73 in any diesel. I had 4.10 in a Power Stroke and mileage sucked my 3.73 Duramax's way out towed and worked the 4.10 Power Stroke plus Top Speed was 82mph and it was rmp'd out.

Transmissions are little better nowadays with more gears and higher o/d gears. Low axle ratios don't bother me.

The �18 duramax is one bad motha, and it can pull wayyyy over 82 mph....

Duramax only used 3.73 as far I as know. Best diesel put in a pickup. Paired up with that Allison transmission, bad son of a gun

I�ve got a 2018 with the 6.6 duramax, I will NEVER own another gas burner as my main truck, maybe for a 3rd vehicle.

x2. I've driven/towed with gassers mostly. Got the Duramax, never again a gasser. Those new L5P's are power houses!

The night and day difference between towing with a gasser and a diesel even with my light of a boat (~4,000) is completely incredible. RV weighs around 6500lbs and I will say, my favorite part about going camping now is hauling that trailer through the hills of East Texas and the hill country. Best part is going up a grade with the cruise on 70, that Allison sticks in 6th gear and you hear that Duramax grunt and groan and chug on along over the hill. Gasser would drop 2 gears and hit 3500RPM.....