Hi Belgiumbarry,
basis is a M30 B35 engine without Kat from 1981 (218 HP), with H-shaft connecting rods, forged pistons (compression 10,5: 1), hemispherical cylinder head and 316-degree camshaft. The valve cover is the original 3.0 CS which fits on the early 3.5 m30 (no motronic).