i have a strange rumblimg sort of grating noise on over run on my escort i have changed all the oils in diffs gearbox etc and there was nothing in the oil or was not really discoloured but doing my head in i thought about takin front prop off to see if it was still there and vice a versa but dont think it would drive because i think it would send power to the end with no prop on am i right in thinking this and help appreciated