Keyless chuck grip is stripped inside and the chuck is stuck in a tightened position. Can I get a replacement chuck grip and how do I get the chuck assembly off the drill, if that's necessary ?

Second question first. No you cant just buy the grip, you have to buy a replacement chuck, shop around for best price, second you have to get the jaws opened up to remove, couple different ways, but first go to Dewaltservicenet.com and type in your model number for a parts explosion. Next if the grip is damaged can you put a pair of pliers on it and turn the collar to loosen it? the jaws have to be retracted to remove the chuck screw (LH threads), what you need to do now is put the drill in the drill only position and the tool in low range. Find a bent handle allen wrench and lock in the jaws, put the chuck on a bench or block of wood and wrench at about a 30 degree angle to strike it counter clockwise, you might have to hit a couple time but this will work. Let me know if I can help further.