Can someone show me a pic or describe where these bypass valves are on a Gen VI 454 block? I need to update my 11 lb oil filter bypass valve to a 30 lb and I also have read in posts that the "center" valve (whatever that is - I guess this was used to direct oil to a block mounted oil cooler in trucks that is not used in marine env). How are these valves replaced or removed? Is the center valve just removed? I have the engine in my garage now and would like to get this squared away before I put it in.