Engine/Tranny is dying,who will win the race?

Hi guys im new on the board as well as to Mercedes.So i took my car to a well known shop "Euro Star Motors"in Spring,and was told the compression on the motor was 185.185.150.185.175,also my fuel plate is leaking at the intake. Transmission takes about 7 seconds and the it jumps into reverse also the fluid is as black as the guys heart that sold me the car and told me nothing was wrong with it. So the question is were do i find a decent used Motor/Transmission.I dont mind paying as long as i get quality.thank-you for the Help