Most automatic transmissions, at least those in cars and light trucks, use a one-piece case. In other words, Transmission and Bellhousing (part that houses the Torque Convertor and attaches to the back of the Engine) are one casting. However, there was at least one Ford automatic that was different. The bellhousing part was separate and had bolts and seals to the front of the actual transmission part. I know because I went to the trouble of installing a used transmission in a TBird only to have it leak all the fluid out. I'd seen that ring of bolts (technically Cap Screws) and didn't choose to check them. Chances are your transmission is not like that, but wouldn't hurt to confirm.
