I was driving my '64 C10 with a 350/4 speed down the right lane of the interstate at about 70 mph. All of a sudden I hear a little bunch of "pinging" sounds, like a small bolt fell out and was bouncing down the underside of the truck. It did it a couple of more times, then I pulled into the left lane to pass a slow mover and the noise quit. I was in fairly heavy traffic, so I was in the left lane for a while and no noise happened. Then I merged right again and before I was even all of the way back, the "pinging" started again. There was no engine sound change, all of the guages were right on so on and so forth. I almost pulled over to see what was coming apart until I looked up to see the problem.
Several car lengths ahead of me was the answer. I was following a soybean truck that was leaking. I was far enough back that none of the beans were hitting my windshield yet.
Man, I never saw that coming, but I'm glad that's all it was,
Scott
