4.3l 6cyl omc cobra

I recently purchased a 91 renken cuddy cab with a 4.3l omc cobra engine. when I went to start it I noticed it was spitting out oil directly from the back of the engine. I noticed there was a part missing but I have no idea what it is. I know nothing about boats. I have been asking around but no one seems to know what part it is. when I asked the previous owner he said he removed it because it was leaking but doesnt know where he put it. he sad it goes to the upper hydraulic line. I know it bolts to the motor because there are four bolts in a trapezoid position with a circular opening that has what looks like louvers. does any one know the part name or what it looks? like my email is [email protected] I can provide pics through there. any help is geatly appreciated