High-Pitched Engine Whine during Acceleration
 

I've put about 20K miles on my 01 GT since I bought it two years ago, its' now got about 101K. Lately (in the last 2K miles or so) I've been getting a very noticeable high-pitched whine that lasts a few seconds during low-end acceleration in all four gears. I accelerate hard regularly but always shift rather cleanly. For example I'll be driving steadily in third gear at about 35-40mph and approach an incline, pressing a little harder on the gas while the cars' cruising at 1900rpm will give me that noise for a few seconds or until I let off the gas slightly. It almost seems like the engine is stuggling mildly at the start of each gear. Does this sound like the clutch or tranny?, I'm sure the engine is fine there are no leaks or loose hoses or what not, I don't know if its' just the mileage and the things due for a tranny flush or what...Thanks for any help. The car by the way is not vibrating, just hesitating slightly during acceleration in low rpm.