coolant leaking from above tranny

[jp <marse@xxxxxxxxxxx>]

    The other day I was doing an oil change on my 1983 733i. I let the
engine warm-up for about 15 minutes. I noticed coolant leaking under the
middle of the car ( upon closer inspection  from an opening above the
transmission ( there are two rubber ports inside the opening)). I lost
about a quart of coolant. I've topped off the coolant and now there is a
slight leak in the same spot after my normal commute (about 20 miles).

Is this my heater core gone bad or some seals for the core?  Am I on the
verge of losing all my coolant if  I continue to drive like this.

Are there any resources describing a suitable repair for this problem?

Any insight will be most helpful.
thanks,
jp

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