The clunk is because the play in the flex disc... when they take it out.
Have them show it to you... new is solid piece together with that sleeve for
bolts to go through... when they break, the sleave is separated from the
The part is not expensive... labor is not expensive either. Long run damage
would be transmission seals at least the rear seal... I don't know how much
damage it will do to your tranny internals... with vibrations... can ruin
the clutch packs and seals.
Then there is your center bearings that ties the two driveshafts together...
Lastly, the vibration will damage the rear end seal also.
Lastly, yes, it will leave you stranded if it destroyed the flex disc bad
enough With hard clunks that you can't ignore... but I doubt it will get to