All options and years the same... the only difference between the SD and the SDL is the longer wheel base and longer rear passenger doors.(to my knowledge... to satisfy the nit pickers) the '87s will have the aluminum head. I wouldn't worry about the wheel base difference...I'd pick the best car if two were side by side. You could have some hell of a party in the back seat of a SDL
Some others can better inform you on the years of 6cyl aluminum headed 3Ltrs that were better that others. I DO know that MBZ did some modifications on the later aluminum heads.

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My Truck.. 2007 DODGE, 5.9 Cummins, 6spd stick, 4X4. My car..1977 240D, OTHER WHEELS...1955 VW Oval window bug, European Delivery (Holland) with a 1700cc, 2 barrel, Porsche drum brakes. 1939 WILLYS Pick-up. 1967 Triumph 200cc Tiger Cub. 1976 Honda 550F 4cyl Motor Cycle.