I just did this last week. I unfortunately don't have a pic but I'll attempt to describe it. It should have a little bit of black carbon stained on the inside(at least mine did). If you look into the injector port it has cylinder shaped recess in it. The injector o ring has the same shape on the side that fit into it. one side has a funnel shape it face out of the block. other side has the cylinder shape(inside block).
Hopefully that helps
