so the bearings will be driven out front to back? Then driven back in from the front? Is it ok to change first 2 but not the others? I know im limited with it in the truck. The gashed area is not on the bottom but at about 145 degrees from top. Could it be alright to leave alone? Also if i decide to replace the first 2 , how can you tell if oil holes line up? Where do i get this tool and would it be a standard size bearing for a 390? Hate to ask so many questions but want to make sure i get it right.