help diagnosing sound

need help pinning down a sound on a '95 rodeo i'm looking at. truck has 115k, 3.2, a/t, fair condition. upon test drive heard a slight "tick" for lack of a better word. seemed to fade almost entirely the more i drove but actually disappeared when i tested the 4wd but reappeared when back in 2wd. very slight tho'. my ears work good and the sound was definatley coming from engine bay and it did not seem related to tranny etc. but i'm no expert thats why i'm here. truck appears pretty solid on test drive. didn't run bad at all considering age and condition. only other noise came from the blown out shackle bushings. thanks for any and all replies and please feel free to add any other info you might deem helpful for this truck.