1994 Chevy S-10 Cracked block or head gasket and freeze plu

Cracked block or head. Sorry.

If it was only a freeze plug the water wouldn't be inside the engine. And if it was only a bad head gasket it wouldn't leak from both sides as well.

The question then becomes replace the engine or replace the vehicle? IF the body is in good shape and the rest of the drive train is OK then an engine would probably be OK. If the body is rotted out and the rest of the chassis is in poor shape strip the good parts, sell them on craigslist or Ebay and scrap the rest.

Heater freeze plug on drivers side was leaking, I could see coolant leaking from it and felt in there and it was loose, I pounded it back in and the massive coolant leak stopped, and there has been no other external coolant leaks.

I added coolant and then waited and could see coolant dripping out of oil pan drain hole.

I added new oil, flushed radiator and added K&W block seal and was able to start and run engine for the 30 minutes. The oil became a light tan milkshake consistency, so there is still coolant getting into the oil, but the engine ran very smoothly with little white smoke from the exhaust.

Could this be the notorious 4.3 intake manifold gasket leak? And that someone added straight water to the radiator and when it got cold that popped out the freeze plug?

Does a bad intake manifold gasket allow water to seep into both the cylinder and oil pan?

The intake manifold change that caused the problems with leaks was made in 96. Prior to that they used a good gasket and proper clamping as well.

The earlier ones didn't have many problems with leaks although if it froze enough to push out a plug it may have broke through. Not real likely that it would leak both ways though.

Hard to say without having it in front of me and apart.
I would still bet on a bad head or possibly a split head gasket.

You said you saw coolant on both sides of the engine, did you find the other external leak?

Good luck.

After pounding in the drivers side freeze plug (heater), there has been no other leaks, the leak must have run over to the other side before dripping down.

Engine is running smooth but does smoke (white), it isn't making oil anymore after adding a can of K&W block seal.

Well, a new freeze plug heater, $34, and another can of K&W (another oil change and antifreeze) and it runs very nice with no leaks, no making oil, and very little white smoke. Drove it hard for a 1/2 mile and no problems. With taking it easy on it for the cold Wisconsin winter it should make it through to warm weather when I can pull the heads in my unheated garage. I guess I can't complain about a $500 parking lot find and about $80 of parts.
I really thank you all for your input and ideas, they really helped and I appreciate it.
Thank you.