If you are hell bent on removing the drain plug, buy a replacement drain plug first. Then unbolt the cover and remove the entire cover.

You can then try the heat process that someone suggested. If that doesn't work go to plan B below.

Drill a hole through the center of the drain plug, that metal should be pretty soft, no reason to have heat treated metal for that plug. Run a bolt/nut through it, tighten up the assembly and use the bolt to unscrew the entire plug. Apply anti-seize and install new plug.

If you are lazy and not obsessive (like me) buy that spiphon pump that Diesel911 suggested. That is the easiest. You can pump the old fluid out and then change it again in another month or so. That ought to be sufficient.

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84 300DT Puke Yellow. Totalled after 438,000
84 300DT Orient Red. 169,000 (actual mileage may vary)
2002 Explorer EB (wife's)