Do my RSR Struts need strut spacer and O-ring
 

I am putting front suspension together and struggling with this...

I see this part:
http://forums.pelicanparts.com/uploa...1486554211.jpg

and the O ring"
http://forums.pelicanparts.com/uploa...1486554386.jpg

Here is pic of my strut, I do not see a grove for the O ring and not sure if the RSR strut uses the spacer?
http://forums.pelicanparts.com/uploa...1486554624.JPG

There is no groove, but space on the backside of the bearing race (what you called spacer) for the o-ring

Agreed with Roland. The o-ring just packs the space between the radius of the spacer and the radius of the spindle. it's there to help reduce the migration of oil along the spindle when the grease thins or separates.

The spacer is technically not a bearing race. I think it's actually a collar that definitely provides the sealing surface for the grease seal and I believe it also serves as a stop or thrust for the inner race of the wheel bearing?

Correct, it's the race spacer, see here no.39. Shaft seal is no. 21 (which seals on spacer):

http://forums.pelicanparts.com/uploa...1486587468.jpg