Plunger A10 crankshaft oil seal

[Jackson]

I have just had my crankshaft reground and new bearings fitted.
On the sprocket side of the crankshaft roller bearing was an oil seal, set into the crankcase/chain case wall.
I can't find it anywhere in the illustrated parts list or on Draganfly's diagrams. It is locked in by a number of centre pops.
Can anyone help me please? Is it some strange addition or have I got a later engine (BA10 5713) ?
I've just looked at the 1954 service sheet and it is present on that!
Anyway it was destroyed in removal and I need to source a new one.

[Jackson]

I think I've sorted it myself now.
While the engine has a 53 number, it's either a '54 engine (roy Bacon says that new models were available fm late in the previous year) or the factory changed the crankshaft sealing mechanism early.