Im sure this has been covered, but I have been searching for two days and cant find anything on my specific question.... Here's the deal, my 40 oil pressure gauge was not working, decided to go aftermarket with mechanical. Heres my question, there is no sending unit on the block. where am I supposed to screw in the mechanical line, and if there is no unit on it now, how is it there is not oil shooting from engine. Does it screw into A or maybe B and it was filled. Thoughts?