On May 12, 2005, approximately 1500 mountain daylight time, a tailwheel-equipped Cessna 150TW, N7866Z, collided with a runway identification sign during the landing roll at Missoula International Airport, Missoula, Montana. The private pilot, who was the sole occupant of the aircraft, was not injured, but the aircraft, which is owned and operated by the pilot, sustained substantial damage. The 14 CFR Part 91 personal pleasure flight, which departed St. Ignatius, Montana, about 15 minutes prior to the accident, was being operated in visual meteorological conditions. No flight plan had been filed. There was no report of an ELT activation. According to the pilot, who landed on Runway 25, he was cleared by the tower to turn off the runway at Taxiway Echo 4. While attempting to make the right-hand turn onto the taxiway, the pilot inadvertently turned too soon, and the aircraft collided with the runway identification sign near the intersection of the runway and the taxiway. The force of the impact resulted in the right main gear leg attachment box being bent and distorted. According to the pilot, there was nothing wrong with the aircraft's directional control system or brakes.