If you are sure that it did not freeze and crack the block, Then the intake manifold gasket is leaking. That is a common problem with the vortec Chevy engines. You need to replace the gasket with a factory Chevy gasket from the dealer.
it might be the intake gasket
It is there to stop the fluids and compression from leaking out.
If it's leaking transmission fluid, could be a bad pump seal. If it's leaking engine oil, could be a bad oil filter, leaking valve cover gasket, leaking intake manifold gasket, leaking oil pressure sender, leaking distributor gasket.
most likely an intake gasket
There is a heater hose that goes to the left rear top side of the intake manifold and that fitting leaks engine coolant sometimes and it will run down the back of the intake around the distributor. If that fitting is not leaking then the intake manifold gasket is leaking coolant in the corners of it. REplace the intake gasket. That's all that can leak coolant on that year engine. If coolant is leaking out between the transmission and engine block then you have a freeze plug leaking in the back of the engine, between the transmission and block. Must remove the transmission and flywheel to fix it.
Water in oil is usually caused by a leaking headgasket. This is the gasket between the engine block and the head. It is an expensive repair.
im guessing someone has told you that you have a 'leaking valve cover gasket'. the valve cover is normally on the top of the engine,above the pistons, sometimes its where you put the oil into. The gasket is where the cover joins with the block.
Sandwiched between the heads and the engine block.
Either a blown head gasket or a cracked block possibly
That is a common problem with the vortec 350 engines. The intake manifold gasket starts leaking in the corners of it. That is where the water jackets are and it's only about 1/4 of an inch wide and when it starts leaking it allows engine coolant to leak into the lifter gallery and into the oil. Need to replace intake gasket as long as you no it did not freeze and crack the engine block.
The head gasket sits between the head and the engine block if it is leaking out where you can see the coolant, yes you can smell the coolant if it is leaking into the engine no you cannot smell the coolant. You can check the oil to see if it has coolant in the oil if it does then the head gasket might be blown.