1995 Oldsmobile Aurora Coolant Leak.

I have a '95 Olds Aurora that I love to death, but recently experienced somewhat of a disaster. Out of the blue, the engine began leaking a considerable amount of coolant; enough to drain the reservoir in about 10 - 15 minutes. The leak appears to be coming from between the transmission and the engine; that is, on the "back" side of the engine, nearest the firewall. My grandfather suspects either a cracked head or head gasket, neither of which are extraordinarily appealing to me considering the costs involved in such a repair. Is there anything else the problem could be, such as a ruptured coolant hose, perhaps to the heater core? I'm unfamiliar with the location of the heater core, so I was wondering if it was in that general area. It should be noted that at the time this problem arose, the engine was not under any stress or even at its normal operating temperature. I had just started the car about 5 minutes earlier. Any help you could give would be great.