Try using a piece of broom handle about 3' long. Put one end on the engine (like you would the stethoscope) the other to your ear. You will be able to hear noises in the area you are touching and not picking up all the other noises like you would with the stethoscope.

51 GMC 100 with 59 chevy 261 under the hood.
3 on the floor with 3.42 gear.