I have never seen a freeze plug fail like that unless there is a potential to rust. If the plug in the back of the block is leaking you will have to replace it. This will involve either removing the engine, or dropping the tranny and doing it from underneath. I would first make absolutely sure that that particular engine has rear freeze plugs, remove the inspection plate to the bell-housing and look in there. It could be a leaking head gasket running down the back of the engine too. Also keep in mind that when driving everything goes back, so if you have a leak in the front of your engine, the air and momentum can push it back, this makes it difficult to find leaks, especially oil leaks. Is your cooling system staying pressurized? Have you had the coolant analyzed to determine if there are any contaminants? What about your oil? any coolant in there? before you get involved in dropping a tranny or removing your engine, check it all out first! Do you have a manual on your car?
Does anyone on the board have experience with these 280 engines? Do they have freez-plugs in the rear? Let us know what you find out!
Regards,
Brian