where is the drain plug that is located in the rear I have water in the back I can hear

the only drain plug in town is located at the base of the radiator. Some manufacturers are nice enough to give you a 'belch' valve at the top of the heater core...perhaps this is the one you'd like to use...if it isn't there, fill the system and pull the top hose long enough to let the air out~

There may be a rubber plug in the floor pan. Pull the carpet back and have a look. Best thing is to find and eliminate the source of the leak.

'79 is a while back. Are you in the "rust belt"?

~okay, I understand. this has nothing to do with the engine..l instantly think of hamster's solution of shooting a hole with a rifle to drain the fluid...just a thought but like my associate states there IS a rubber bung under the carpeting~

on the vette you will hear the fuel in tank sloshing . so be diligent okulll?

oh really? like a skinny dipper in the bikini pool-

yeah! but to hell with the car if she's in view!

Really Jimmy? no baffles? are you just jerkin' the chains here?

feel like going to the junkyard with a battery powered hacksaw, but if they are like 99% of the 'salvage' yards they take the tank out for safety's sake~