I'm tearing apart my suspension and came across some grooves in one of my upper arm shafts from the needle bearing.  I started this project because I wanted to replace the steering rack and now I'm finding so many things that need to be replaced. Uggh!  I'm wondering if this is a big deal.  Should I replace the shaft and needle bearing?  If I replace one, should I replace both and all four bearings?

Also, can someone explain to me the reason for the offset groove in the collar?

Jamie