1998 Blazer Coolant in Oil, immediate failure

I see a similiar thread, but thought I would just start fresh. My 1998 Blazer with the 4.3 and 144,000 miles has been rock solid with no nagging issues. I drove the car the other night and it tries to overheat, first time. I discover that is is low on coolant, real low. Filled it up and checked where it parks, no sign of leakage. Say to myself I need to keep an eye on this. My son takes it the next day and a couple miles from home calls to tell me he is broke down. Sure enough, coolant is gone! I found it, it's all in the crankcase.

So I was thinking head gasket, but it has been running good and seems to have failed all at once and literally dumped all the coolant into the crankcase. I would have expected a head gasket to be a slower, nagging problem. Tonight I started taking compression tests before dark and the first to cylinders I've checked were both 150#, before darkness drove me inside.

So now I'm researching here and read that it could be the intake gaskets. That would make sense to me too, but would that dump that much coolant, that fast? I did put pressure in the radiator and it doesn't hold at all, just comes straight out the oil fill neck(I had the cap off). So my 2 big questions are:

1. Any idea of what would fail that fast and that catastrophicly?
2. Is there any way to test and be sure of the intake gaskets vs. the head gaskets?

If I knew it was the intake gaskets, I would probably go after it, but if I prove it to be the head gasket(s), it may not be worth it to me.

Thanks is advance for ANY input, John

Its probably the intake gasket.

The intake gaskets are a likely cause, as are the head gaskets, or it could even be a bit of both. If you do choose to dig deep and go looking at the head gaskets, the intake gaskets would have to replaced anyway, just because the intake manifold was removed.