If you are interested in a heavy-duty pickup truck, then you are probably looking for solid towing capacity and payload in your truck – otherwise a standard or light-duty model would do just fine. Even though the diesel engine in the 2020 GMC Sierra 2500HD is the same diesel engine as in the 2019 model, a great deal of work has gone into improving overall performance for this truck. Just keep in mind that towing capacity and payload can vary quite a bit depending on how you configure the truck; using a gooseneck or fifth-wheel setup will give you greater trailering weight limits.
For conventional towing capacity, if you choose the standard gas engine, then you get up to 14,500 LBS of maximum towing regardless of whether you choose a regular cab, double cab, or crew cab. Fifth-wheel and gooseneck ratings do change, however: the regular cab has a maximum capacity of 17,400 LBS while the double cab can handle up to 17,100 LBS and the crew cab can pull up to 16,900 LBS behind it. As you might expect, payload maximums also change depending on which cab you choose: regular cabs offer the best overall payload limit since they can handle up to 3,997 LBS while double cabs can hold up to 3,854 LBS of payload and crew cabs top out at 3,862 LBS.
As you might expect, the more powerful diesel engine gives you better towing capacity, especially for fifth-wheel and gooseneck configurations, but lower payload limits. For conventional towing, the diesel engine with a regular cab and double cab can pull up to 14,500 LBS behind them while the crew cab configuration can tow up to 18,500 LBS. With a fifth-wheel or gooseneck setup, the double cab can pull up to 18,200 LBS behind it while both the regular cab and crew cab can handle up to 18,500 LBS of weight. For payloads, the regular cab tops out at 3,715 LBS while the double cab can handle up to 3,657 LBS and the crew cab with the diesel engine has a maximum payload of up to 3,597 LBS.