Cadillac Repair: antifreeze leak, antifreeze leak, engine leaks

Question
I have a 1993 Caddy sixty special 4.9 liter engine. Bought car drove several hundred miles no problem until now. Notice have small antifreeze leak it does not leak when motor is running I put car on ramps ran it for 20 min no leaks. Cut car off a look it over for couple of min no leaks. Placed piece of cardboard under and checked it in 30 min no leaks.  Next morning it had leaked. I cannot be 100% positive but think it is leaking center front of engine. Leaks out approximately a quart. Is this sound like freeze plug is their one on front center of engine if not where are they at?

Answer
The easiest way to find this type of leak is to remove the radiator cap and put on a manually operated pressure tester pump and pump abot 18 lbs of air into the radiator cap was and this will build up pressure in the cooling system and will cause the leak to become visual.