The Classic Machinery Network

The S with the engine number may have been a factory replacement engine or something out of a non tractor application.

That is how I understand it, but I expected the S to pre/suffix the number, not be on it's own on the other side of the engine. To be fair it's a bit of a non issue as it's made of so many other parts it will only be a question of do I include the S as part of the engine no. when applying for a V5?

If on the other side I am not sure if relevant? Have you tried dating the engine number?

Yes, the casting code on the block and the serial number (minus the S) for the engine match datewise, so I guess theoretically the number stands.