On October 13, 1995, at 1932 eastern daylight time, a Mooney M20K, N3983H was substantially damaged following a collision with terrain during a forced landing attempt near Dalton, Georgia. The commercial pilot was not injured in the accident. The aircraft was being operated under the provisions of 14 CFR Part 91 by the pilot. Instrument meteorological conditions existed at the time, and an instrument flight rules flight plan was in effect at the time of the accident. The flight departed Marietta, Georgia at approximately 1900, and was destined for Rockford, Illinois. The pilot reported that during the climb, at about 7,000 feet above mean sea level, the engine manifold pressure dropped to about 22 inches, and the engine oil pressure dropped to zero, and he advised air traffic control that he would need to execute an emergency landing at the Dalton, Georgia Airport. During the emergency instrument landing procedure, he overshot the intended runway, and impacted the terrain. Examination of the aircraft revealed old oil stains on the underside of the aircraft, from the engine cowling trailing to the tail. Examination of the engine revealed that the number one and two connecting rods had failed as a result of thermal stretching and breaking of the rod bolts. No oil leakage path was observed during the examination to indicate that the engine was leaking oil at the time of the accident.(See Analytical Inspection Report Attached to This Report.)