Besides the o-ring on top which I took it off to replace a new one, is there suppose to have another o-ring between the pintle cap and the base of the injector? Or is it's fine the way it is shown in the picture.
This is a RC 1000cc injector for B series motor setup that I got used from a member on this board.

 

Looks fine to me.
Replace one on top, add rubber bung and your set.

 

what rubber bung? You mean add a O-ring on top? I have new ones, I'm just not sure if the bottom of the injector is missing something.

 

all it needs is a washer on top(fuel rail side)
and the the thick spacer/washer thing on the bottom...these should be on your stock injectors right now...the black things that fit in the manifold, just swap them over to the new injectors

 

Thanks!