Martin,

I bought one from Enya - thinking to convert my early model 11CX to diesel, and it will only fit if you also get the diesel cylinder.

The 11CX bore is around 14mm while the contra diameter is 15.7. The same head is used on the 15 diesel as well.

Luckily for me Enya has a good returns & replacement policy. In fact Ken Enya is s delight to deal with.

Never did convert my 11 CX to diesel.

So to answer your question, the engine is the same as the glow except for the cylinder, which is recessed on the D to take the contra.

G