Well thanks to all who replied back in February.
Problem: Dull clunking noise coming from the front end of '91 Acura Integra LS - 5 spd... ***but*** only at a very particular driving circumstance of coasting to the bottom of one particular steep hill in 1st gear, then making a very sharp right onto an upward hill and shifting into second after making the turn. Somwhere in the turn and shifting the clunk would occur but not every time.
Sounded like some kind of suspension or mount etc problem.
Well the car stranded the driver immediately following the final clunk which was a particularly louder and bigger clunkier clunk (as i was told).
Car runs fine, the engine cranks easily , no obvious noises, clutch feels the same, transmission shifts or feels like it is shifting and when you look under the car everything seems to look normal (that is nothing is hanging or drooping or fallen out )....
The only diagnostic of any note is that when you press clutch and shift into higher 4th/5th gears and release the clutch you hear a buzzy/whiny noise that increases it's buzzy/pitch with the revving of the engine but at lower gears the noise is almost in-perceptible.
So anyone care to have a guess at the problem ? (answer below) robb . . spoiler space . . . . . . . . . . . . . . broken inboard joint on right driveshaft