On September 22, 2000, at 0750 hours Pacific daylight time, a Grumman-Schweizer G-164B, N8981H, was substantially damaged when the aircraft nosed over inverted during an off-airport forced landing near Tracy, California. The forced landing was precipitated by a loss of engine power. The certificated commercial pilot was not injured. Visual meteorological conditions prevailed for the aerial application flight, which was operated by Trinkle and Boys Agri Flying, Inc., under 14 CFR Part 137. No flight plan was filed for the flight that departed from a private airstrip near Tracy at 0740. The pilot reported that the aircraft's engine lost power, and, during the ensuing forced landing, the aircraft rolled through a muddy bog and nosed over. Postaccident examination revealed that the number 1 connecting rod failed. The engine time in service since overhaul was 721 hours.