1 ton differential with 3.73 gears

I have a 97 HD k2500 and want to convert to a 1 ton. The truck specs indicate the same front end weight capacity on this truck as a 97 k3500 but the rear end does not have the same capacity. I do not know if the actual housing is different or the 2500 just has lighter springs and/or frame under it. The reason I want to do this is that the highway weight restrictions are getting tougher in my part of the world and the load I am carrying requires a 1 ton (dual wheels). My truck has 3.73 gears and I am having difficulty finding a 1 ton diff. that is not 4.10. Does anyone know if 3.73 was available for these trucks? Can I install a newer diff from 2001 and newer because the Duramax equipped 1 tons are available with 3.73 gears?

The reason you are having difficulty finding a 3.73 dually rear is exactly the reason you want one. Weight capacity. Not necessarily the axle weight capacity, but the GCWR. The Duramax truck axles are ONLY available with 3.73, while the previous Diesels had options. To have the highest capacity, the 4.10 gears were required. The same truck with 3.73 was significantly less. You may only find a SRW axle with 3.73 gears, which is what you have now.

Another option would be to get the axle you find, and re-gear it. A refresh of a used (possibly well used) axle may do you a service.

Of course, when it's all said and done, it may have been better to just get a truck that meets your requirements, and dedicate it to that task.

Even if you change the 2500 HD single rear end to a 3500 duel wheel rear end with the correct ratio under Ab and Canada (for that matter north America) DOT regulations will still recognize the truck as a 2500 and your GVW will still be the same. As D-max pointed out find a truck that meets your needs and dedicate it to the job in hand. I Know From first hand experience when i got stopped at a road side check and had to prove that my duelly was in fact a one ton from day one and not a conversion. It was a trip to the nearest chev dealer and a notary public to get everything legal so i could continue alomg on my merry way (only 40 miles one way). It did not help matters that i had a 12.5 ft camper on and pulling a 18ft trailer with a full size p/u on it. When all said and done they said have a safe trip and a nice day.

Thanks guys. I have not investigated but I have been wondering how I could possibly get away with this, legally. My wife and I do a lot of travelling, (I love to drive when I have the rig wih power) and will be doing some travelling in the US. I was wondering if there is risk of getting checked for this kind of stuff. I am very happy with my truck but just wanted to increase the capacity. This could be an excuse I can use with the wife to get a new truck, but I have to admit, the new GM's do not appeal to me. I do know a guy with an 05 Dodge 3500 Quad cab, 5.9 liter Cummins, 6 spd man.
One guy told me I could buy a "dual wheel kit", I searched the internet and the feeling I get, this is just for those that want the dual wheel look.

Some states in the US allow registered weight capacity according to the fee paid. These are usually also required to have the GVWR # posted on the side of the vehicle as well. I've never heard of this in Canada. You could possibly have the vehicle re-registered for a higher capacity, but it's probably not worth the effort, or cost. Also, the added weight of the conversion takes away from the GVWR. Otherwise, dually conversions are just for looks, like you said.

anything ate 80s and up will work the axels all fit right to 2006 i know this because i have relaced internals with parts from 20 year old trucks in both my 01 and 06

yeah dual wheel conversions wont increase capacity other than spreading the load out over 4 rear tires instead of 2, but they also help reduce trailer sway by giving you wider track and more contact patch in rear. I feel about same as Dmax I would probably sell or trade in current truck for one witht he higher weight capacity if you really need it, a trip to local scales while towing your "normal" heaviest load will tell you if you are within your specs already or not. no sense in trading up if your current truck is already more than you need.