1983 Ford Fairmont engine whine

Lately I have been hearing an engine whine when I am going about 10-20 mph then again from about 30-40 mph or so. I thought it might be coming from my stero, since I have an amp, but when I turn off the head unit it is still audible. It is most noticeable when I am decelerating through 40-30, whether I am brakeing or not. I have checked the transmission fluid and all the grounds, and they seem to be good.