Websites such as Moss Europe show it as an alternative for any Minor engine, but it's also listed 'NCA'.
Was this really the standard fit on the 10MA engine? There's no mention of any alternative housing in the AKD 3541.

Has anyone actually got one of these on a 1098 engine??
I thought all the 1098 Heads had the position for the Temp Sensor?

They seem impossible to find these days, Part Number 12A 408... apparently also used on some Mini engines.