I'm looking at the O.S. line of .12 engines, and they have 2 different kinds of ends on the crankshaft.

One has a very short threaded section. The other one has a short threaded section followed by a smooth section. The smooth section is at the end of the shaft.

Which one do I want... threads only, or half-threaded and half smooth?

Which is the one I want to use for a AE NTC3?

Thanks for all your help.

Dean
Alberta, Canada.