I bet the block is busted either under the intake or the outside beside a freeze plug. I work on car and boats with my dad all year and 99% of the boats that come in and haven't been winterized will have some freeze plugs left in the block and it'll crack the side out. Sometimes even when the plugs have come out, it'll still freeze and that's at lows around the 20s. And x2 on what 73 fsj wagoneer said, watch for white smoke and milky oil.
Can you get your hands on a kerosene shop heater? If it gets cold again it will crack if it has not already! When I was little I put water in a foam coffee cup and each week I would check it and it would be bigger each time till the cup broke! Even after its already solid ice it keeps getting bigger and bigger! I would heat it up soon for better luck! Or also maybe a small camp stove under the engine? YOU NEED TO HEAT IT UP!
I don't think I can get my hands on one by the time the weather breaks anyway. I hate to sound like this, but I do have a Centerbolt 350 sitting here with a stand alone throttlebody injection kit on it. If this engine is toast, I will just call up transdapt and put the Chevy in it. I am a diesel man myself tho, I would much prefer to put a 6.6 LBZ Duramax in it, but what I have is what I have. But honestly I have put that engine through hell and back, she's a trooper, I think she'll pull through this one.
I don't have the money at this juncture to be buying anything like that right now. Like I've said I've put her through far worse. I know she'll pull through. The main point was, when I realized what happened I felt so stupid that I wanted to know that I was not alone.
Welp, I will consider myself boned until I can borrow a lift. I poured a gallon of antifreeze in her, everything seemed fine, so I walked back to the house to fill the jug with water, came back to find the antifreeze GUSHING from somewhere between the engine and trans in that area. I didn't bother crawling under it, I just did the AMC walk of shame back to my apartment and moped for a while.