Coolant leak problem found? Maybe

I have a 420 SEL w126 chasis with a coolant leaking problem.

I finally think I found where my coolant is leaking from. It seems a hose was cracked. I looked down and I could see the coolant spitting around. I took off the hose, and notice it was cracked.

Can anyone tell me what hose this is? I'm assuming it is a coolant return or supply hose. If i trace it, it seems to go from the engine block to the heater core at the fire wall. There are what seems to be 3 hoses here. Any idea which one i'm looking to replace? And what part #?