I am new to this site, so forgive me if I make any mistakes. I have a 1994 Cougar 4.6 and i have noticed a transmission noise while accelerating. It is best described as a high pitched whistle noise, and it gets louder as the rpms go up and as it shifts, then it fades away. It only seems to be present during the 1-2 shift and 2-3 shift. I have narrowed it down to a transmission/driveshaft or rear diff noise because i can rev it in park and it wont make the noise.
Any help would be greatly appreciated. Thanks