well for the 760 i'd inspect the rear self leveling Boge shocks. If after a short drive with nothing heavy in the trunk the rear end is sagging you probably need new ones. When they fail it costs lotsa $$ to get another one. The 760 has lots of electronic toys so you will need to test them all out. Test as many of the switches as possible. Especially make sure the ACC is in working order as it is an expensive piece. Make sure the turbo is working. Find out when the last time the timing belt was change. Look at the condition of the radiator, hoses and overflow tank. And then obviously the usual stuff... body rust, look under the car... yadda yadda. Good Luck!
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1988 760Tic - 155,550 1966 M-B 230 sedan - 98,000 - Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us. - Bill Watterson