I got what you were saying right off, Cal, but let's clarify a little. Welch plugs and freeze plugs are different. Yall may clump them all into one name down there, I don't know. A welch plug does not have the "wall" around the perimeter of the plug. It is a convex plug that fit into the casting holes in the block, but they are for blocks with a stepped recess, such as the early Hemi. They install against the stepped ridge and then, you take a hammer and place it on the center of the convex area and flatten it using a second hammer. This flattening action causes the welch plug to expand and locks it into position. Of course, a little sealant is applied, much like a freeze plug. The freeze plug is for a hole without a step, like the LA or B series engines and had the wall around the perimeter. They are simply a press fit without the step. Sometimes the terms freeze plug and welch plug are used interchangeably, although that's technically not correct.
