Nathan, you probably know this already, but, when ordering bearings for the SF/RF series be sure to check whether you have the original case or the later case. These engines were produced with two different sizes of rear bearings.

The early cases take the 17x30x7 #6903 bearing, while the later ones take the 17x35x8 #16003 bearing.

You can tell the difference from the outside of the cases. The #6903 model has a stepped-down area where the bearing is housed.

But, then again, maybe all RF's had the larger bearings; that I'm not sure about.

David