coolant leak

Has anybody seen a coolant leak coming from the rear of the engine? I have 1990 2.2 Liter 5 speed manual shift Cavalier.
The leak is near the rear and back (firewall) close to the heater hose outlet but lower. Near a round object bolted to the block that I can't identify. Anybody have any suggestions? I have had this car since new and I know the car well. I'm past the obvious problems.

obvious problems such as the heater core? it would drip or run out of a drain located in the fire wall

obvious problems such as the heater core? it would drip or run out of a drain located in the fire wall
That's what I am saying! I know already about the obvious leaks like the heater core and such. I am looking for a leak on the backside of the 2.2 liter engine. I'm beginning to suspect a head gasket leak. Anybody had a leak on the rear driver's side of the engine block?

To determine if it's a head gasket.Do a die test, which any good mic can do for you.