Yup, that's normal. If you pull the heater hose off the radiator fitting you'll see that while the barb is pretty huge at 3/4" the actual hole through it is very small, like 3/16" or something - the setup basically ensures there will be some coolant going around the transmission cooler in the bottom tank of the rad to help warm it up faster (automatic transmissions don't like hot ATF, but they don't like it too cold either). If you're replacing the heater hoses, you don't have to buy this assembly from the dealership - all you need to do is carefully cut apart the aluminum crimp collars that hold the rubber hoses on the steel fitting (Dremel tool works great for this), then you can slice the hoses with a razor blade and you end up with a bare steel T-ee fitting with barb ends - slip your new hoses on that, put regular hose clamps on them, and you're good to go. Or, if your truck warms up fast and you don't really drive it anywhere till it's warm, you can just skip the T-ee setup altogether, and run a hose from the engine block/head straight to the heater, and plug the port in the radiator's bottom tank with a 3/8"-NPT solid plug.
. I'd never seen one set up like that before, and it made me go 
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