Hello All, Just got to exposing the heater core on my ancient '88 740 GLE. "What a nightmare" barely describes it!! The best that can be said is that the central housing/plenum breaks away from the A/C part. Am using the Chiltons manual, which covers 140 to '88 740-780. The instructions are very brief - like "Remove central distribution unit" no mention of how many screws to look for. Well, 25 years is the life expectancy, I suppose. The symptom is the strange fogging of the windshield, and all four carpets icky sticky wet, and loss of coolant, of course. Have lost count of how many trim panels, etc. have been removed. Hope that some designers can come up with cleaner concepts for the future. Shorting out the core hose ends was a cinch - just take a 2" length of 1/2" copper house piping, and solder a brass compression ring at each end - maybe find a suitable plastic equivalent? Omar Jette, Montreal