The Stanley 78 is a duplex fillister rabbet plane. Because of that, the right side of the blade needs to be flush to just-ever-so-slightly proud of the right side of the plane body. The left side doesn’t matter much since this side normally doesn’t engage the work . The plane should have a fence , a depth shoe, and a nicker in front of the blade which is rotated to engage it for cross grained work. Many times these parts end up missing and owners don’t realize it because they aren’t familiar with the plane. You can still get use of the plane even if those parts are missing if you use it in a manner similar to a wooden rabbet plane. I have several of these and they are among my favorite types of planes.