Thanks for the info.

I located the heater core, and I don't even want to get started dismantling the car to get at it.

As an even quicker fix, and as the car is 16 years old, what about the pros and cons of Stops Leaks?

The way its looking is;
1. Bypass and no heat or
2. Stops Leaks

thanks again

i did one in my 85 760. i had it out in an hour...but it took me 6 for clean up and reassembly. and yes its buried all the way on the firewall on the inside.
(i had the dash off before to replace it, its not to hard..just time consuming. the trick is to goto a bone yard and tear one apart so u know where every screw and bolt is, and not have to worry about breaking anything.)

In the past I used with great success Aluminumseal.They are little tubes filled with tiny aluminum flakes.Great product.Fixed a leaking heater core in a early 240 about five years ago and is still holding up.

Stop leak is the eventual kiss of death for an engine.

Stop leak is a temporary fix: sooner or later it will blow out because the underlying corrosion is still at work and the core is weakened. This blowout usually occurs when you have grandma and the kids in the back, stuck in traffic on July 4th (i.e., the worst possible time.)
A more permanent fix is to bypass the heater core entirely in the engine compartment with a new hose. Wear a coat in the winter.

I'm inclined to go with the by pass. I started to get at the core and there is a fair bit of coolant in the ducts. I think the previous owner had tried the stops leaks trick, judging from the colour of the coolant prior to my flush and fill.
thanks for the input.