Well....
This engine must E34 or 1989. My reasoning being different bits and pieces. In 1987 for a brief period they used the suffix 808 manifold. Three bolt and clocked differently as to the three bolt pattern as Sven had noted earlier. These manifolds are cool and are ported quite nicely. 50 cc larger in volume than the suffix 603...stock for the E9. The two bolt manifolds, suffix 816, ball and cone style, with 2 inch downpipes did not happen until 1988. Also changes were made as to the thermostat housing in 1989, near as I can figure, with more ports for additional senders for motronic. Please feel free to correct me if you believe this information is in error.