What causes a 1991 Subaru Legacy LX to have a knocking or ticking noise that almost sounds like a flat tire only when you accelerate and no noise when you coast and could it be low transmission fluid?

Answer 1

Turn the car left & right to see if it knocks... do it both with the throttle. if it doesn't knock during a coast or idle, you're fine, and if it knocks when you accelarate, you're still not TOO lethal... spend 80 bucks, get yourself a new pair of axles, as this knock is the sound of the bearings going out. your engine is fine!