I know where the leak is, but I am having trouble identifying the part. It is a hose that connects to my firewall which leads to the heater core I believe, and it connects to this part that I can't identify that is also leaking. When it leaks it drips on the exhaust which causes steam.

 

 

That heater valve is vacuum operated ( small plastic hose connected to the top) so that hot water is only directed through the heater core when the heat is on and doesn't mess with AC operation. It's pretty sturdy and doesn't normally break or crack, so I'm guessing one of the connecting heater hoses is split or swollen from age and needs a clamp tightened down more or the hose(s) replaced. Or inspect and replace valve if damaged.

 

OOPS, in case you were referring to the hose above that, ignore the above response

 

Yeah that hose is a bit swollen and needs to be replaced, but I think the hose to the left might be leaking somewhere near where the hose connects to the firewall to the heater core, because I noticed coolant steaming from the back of the engine right beneath that hose.

 

The heater valve u said it was, I need to replace because I've noticed it is leaking from the bottom of it, but thank you for identifying it because I've been trying to find out what it is, and my 1988 firebird repair manual doesn't have a diagram or any information on that part. Hope I can get it repaired it soon.