I have a 66 with a 6 cyl. that makes a funny sound when I accelerate, only when I accelerate, only when I am in drive, and only over about 10 mph. The sound is sort of a rattle, sort of an intermitent squeal. If I am maintaining constant speed, or have my foot off the gas, the sound goes away. I searched under the hood, and nothing seems to be loose, all the fluids are fine, and there appear to be no leaks. I recently replaced the timing chain, and rebuilt the carb. Any thoughts, this one has me baffled.