JE. Why would you want to replace an oil pan for a drain plug that doesn't want to come out? If there's enough of the drain plug head left to get hold of, just impact it out. If, on the other hand, the bolt head is damaged, then use several cobalt drill bits, starting with a smaller one first, to drill out the drain bolt. Center punch and then drill slowly. At some point along the way, when the bolt head is mostly drilled away, the remainder of the bolt will probably turn out by hand. If the pan threads are damaged (and they probably won't be if you've drilled carefully), a very effective repair is a TimeSert. Probably better than the original threads. Returns the hole to the factory thread pitch and dia. Then just buy a new factory drain plug w/ seal ring and all should be well. Can't imagine the whole job taking over a couple of hours.