Single castings, paired banks and built-in injectors
The inline diesels each use one aluminium head, but they are not simple parts. The 300Tdi runs a pushrod valvetrain from a belt-driven camshaft, modified from the earlier 200Tdi design. The Td5 head is a cross-flow casting whose overhead camshaft works the unit injectors as well as the valves, and the 2.0 Ingenium diesel goes further, integrating the exhaust manifold into the head itself.
The TDV6, SDV6 and supercharged 5.0 V8 are vee engines, so each bank has its own head. Left and right are different parts, and a fault on one side needs only that head. Compression ratios differ too: 17.3:1 on the 2.7 and 16.4:1 on the 3.0, so give us the engine size as well as the side.