[chrisf]

ok, I just measured the thread OD for the oil tank drain plug, it is just over 21.75mm in diameter.
I can only assume that this is a 22mm x 1.5 thread (the pitch was definitely 1.5, same as the engine case plug).

Could the engine oil plug be a 20mm x 1.5 thread !?!? Another little bit of info: The engine case oil plug bottoms in the oil tank, no thread interference or hint of engagement. The oil plug from the tank will not even begin to engage the threads of the drain on the engine case.

I am trying to size a correct banjo bolt & eye fitting to rig up a oil return system for my turbo!

thanks,

~Chris