To answer your question, there is no freeze plug between the engine and transmission. Freeze plugs are the result of the engine block's manufacturing process.
Whether you are manufacturing one engine block or thousands, the process is the same. An engine form is creating in a block of material. The form is a hollowed out reverse image of the engine into which molten metal is poured and allowed to cool and cure. When the engine mold form is cooled sufficiently, it is hauled out of the material and cleaned so that you have the engine casting. The engine casting is then cleaned further to remove rough spots and other imperfections.
After this and any further cleanings, the engine casting is sent further down the line for more work and assembly.
During the casting process, there are holes on the surface of the form through which the molten metal flows to fill the form. Once the engine form is filled, a small amount of material is allowed to fill the access tunnels and cap them off. When the casting is first removed from its form, it will have some metal "legs" that protrude from the bottom of the casting. Those "legs" are cut off near the surface of the casting. They are known as the freeze plugs. They plug the casting while it freezes or cools, thus the name freeze plugs.
Engines and transmissions are joined by the clutch and clutch plate in both manual and automatic versions. You can find further information about cars and repairs by looking at: www
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