2005 Legacy 2.5i /4eat trans prolems.....

[Legacyguy005]

Hi All am new on here-Well just picked up a 2005 legacy today-bought it w/transmission probs-cars in nice shape overall-but the previous owner thinks the trans is toasted-now I got in it today-cranked it up-and when i dropped it in drive-I can feel a 'good strong pull.... not like somthing w/a baked tranny-when i put it in reverse-same thing-the last owner told me what happens is once you go out on the road with it-it dont take long-the trans "fades away'-to the point where no gear you shift into will do anything-[car dont move]-I couldnt take it out to try it-[no plates-he had allredy taken it off his ins-an off the road]-also after it get up to temp....Theres a "low picthed' whine coming from the torque converter area-it was getting louder as the car ran idleing for a while-Am wondering if the trans mabbe should come out-an apart 'for an "exploratory'-or I  should just look for a good used unit-the number on the bell house is :TZ1B7LCAAA2D-Also  how can i find out the final drive ratio for another-so i can chec w/whom -[or whereever] i buy 1..... any info would be helpful-thanx-bobby