Upon looking at your picture, do as another poster said and take it to a machine shop, however they will not guarantee any results.
Try soaking the threads with PB Blaster maybe...... then remove the plug(s) if they loosen up....
If you're OK with leaving well enough alone, leave it alone. There is maybe 1 - 2 quarts of water at most (in each). Optionally, open the chamber through removal of the riser (not my first choice) or remove the forward hose at the thermostat housing and pour a 50/50 solution of anti-freeze down into the hose and on into the riser chamber. Drain the remainder of the block (two plugs) and the J-tube plug. Pull the hose from the bottom of the tranny cooler to drain that, and it's a done deal.
Or fill the entire engine with the 50/50 solution until it comes out the exhaust. Another done deal.
Last edited by Cloaked; 10-26-2011 at 06:17 PM.