Go to the parts store and ask to see an oil pump . Get them to show you what the sleeve looks like . You may already have it and not know it. I am looking at an old magazine ENGINES, How to make Power, put out by Hot Rod magazine.It has and excellent article on Reality 396,beginning the bargain big block. Parts one and two. You may be able to pull it up or call hot rod mag. and have them sent it to you.