1. Reciprocating engine exhaust system designs commonly used to provide for ease of installation and/or allow for expansion and contraction, may include the use of 1. spring loaded ball/flexible joints. 2. slip joints. 3. bellows. 4. flexible metal tubing. A. 1, 2, 3, and/or 4. B. 1, 2, and/or 4. C. 1, 2, and/or 3.