Oil drain plug
 

Ok guys I have a question. Is there another size drain plug for these 4.0s my 96 I have bought two drain plugs that haven't fit. Both r a size 1/2 by 20. Is there another size for them. Bc they r to small

Is it possible that in the Jeep's past the drain hole got stripped and was tapped for a larger diameter? A digital caliper gauge with an inside-diameter feature and a thread pitch gauge could probably get you the dimensions you need. If you don't have them handy, any local shop would probably check it for free or minimal cost (they'd probably even have a spare drain plug floating around to fit).

^ I would guess this to be true also ^