i know i'll probably get heat for this, but you guys really need to read before posting. i think just about every one of your replies has told him something he has already done. i'm sure he's getting pretty tired of repeating himself over and over.
so you have the valve cover off, oil drained, plugs out, belt off, and it still won't move. you already know that you should remove the exhaust and pull the oil pan, so i'd go with that for now.
now i'm not 100% sure on this, but if i remember right, you should be able to unbolt the exhaust pipe from the manifold and right after the cat. drop it and pull the pan. take your time looking at everything very carefully and most likely you'll be able to see where/what caused it to seize. if you need help locating certain parts on the vehicle or other detailed information to work on your jeep, go to
www.alldata.com and get yourself a subscription for your vehicle. i think it's like $15 a year. it helps alot. it's the same software that most dealerships use.
also while your down there, just pull the starter, just to make sure. disconnect the battery, remove cables from starter and remove starter. now try turning the engine again. chances are that's not what's blocking it, but it would suck if it was and you didn't try it. it's something simple to remove.
edit: i just thought of something else. i doubt this is it, but make sure your cat didn't suddenly colapse or you have some other exhaust restriction. i don't think it should kill the engine that fast, but we did have a car at the chevy dealership that wouldn't run and it had a potato completely sealing the exhaust shut. so if for some reason something clogged your exhaust 100% shut real quick, then it might be possible that it could have killed the engine. doubt it, but possible. just seems weird that your engine would lock up without even the slightest sign of wear/metal in the oil when you drained it. you did drain it into a clean clear container right???
