Firewall to tranny coolant leak. heater core?

[cocofunk]

I have a coolant leak from the rear of the engine, firewall, which drips onto the tranny and onto the floor from the tranny.

I checked the plastic "Y connector" which bolts onto the head, and it does not seem to be that. That connector is on the passenger side, and my leak appeears to be more on the driver side. Additionally, I see moisture/water seeping from the heater core plastic connection (the one at the firewall) which connects the hoses to the heater core.

Is this leak common? How to address this? New heater core connection part needed? Is it a bad idea to bypass the heater core since I will be using this car for track anyway?

Looks like 6 on this diagram. http://www.realoem.com/bmw/enUS/show...diagId=64_0663

Also FYI - car has been sitting for months and I have replaced, H2O pump, tstat with housing, timing cover gaskets, front seal, rear seal, oil pan gasket, oil filter housing gasket, oil filter housing bush. Now it turns right on, no prob, just have this leak - may have happened when dropping/rising the engine when doing the oil pan job.