My (failed) engine is an SL prefix one. It used to have all the MKIV parts, but just as Rob’s photos show, the factory moved the belt line one inch forward for a reason, on cars with the steering column on the LH side, there would not be enough room.
The damper is the same part, but it is mounted 180 deg offset, that is mirrored along the axis of the crankshaft. The pulley on the crank is different and they can be exchanged, but the MKIV setup places the belt line one inch closer to the engine block, so also the waterpump should then have the thin steel backplate, when the MKV setup places the beltline one inch away from the engine block and requires the thicker casted aluminum backplate betwen the engine block and the waterpump.
But these dampers do not cause vibration and can be tested without one. I think brother Nantes said the damper (against harmonic vibrations at 1200, 2400 and 3600 rpm) was only installed after R&R had trashed a 3 1/2 Litre beyond it’s limits. Of course any non-balanced rotating mass will create vibrations.