Thanks to Brian Carlton,gsxr, and many,many others. I have a 87 300DT. Without your help I wouldn't have bought it. PLEASE don't get mad if I didn't personally reconize you. I read hundreds of threads and didn't write down all the posters names. If you posted on the 300D THANKS!
It only has 107,000 miles. Interior excellent except for tear in drivers seat. Paint has some clear coat coming off, but you can't tell from 20 feet away. I paid 2500.00. I checked the heads with the "heat it up and check pressure in top hose" test. I also checked it the following day. Seems to be OK although I know it could go at any time. Checked blowby. The oil filler cap resting on the valve cover has no movement. It had a vacuum leak to trans. By reading your post I knew it could be fixed. When it changed gears it clunked so loud it sounded like the rear end was going to fall out. I bought the car and a Mityvac. Found the emissions leaking EGR and AVR. Plugged them up. Found numerous leaks. Replaced rubber hoses. It still clunked. Checked the diagram againest the car. AH-HAH. One of the hoses was routed wrong. Rerouted correctly. Smooth as can be. Shifts fine.
I still need to replace all the lines and fittings. I'm also going to replace the vacuum pump(original), trans mod.(it has slow leak), water pump (for insurance), fuel lines, flush the radiator and block(it has green fluid in it) , replace all vacuum motors in the environmental controls(middle A\C vent doesn't work and belt pully tensioner(idler or whatever it's called).
The car drives, handles and looks great. I plan on keeping it for a long time. I'm willing to put some time and money in to it and figure the cost to repair as compared to the payment on a really nice car to be a good deal.
Once again Thank all of you very much for your outstanding help in making Mercedes ownership a pleasure.