The "telescoping" part is just a slip-joint, it slides in and out to allow for length variations due to the articulation of the axles under compression and rebound. It is not spring loaded or under any pressure for or aft. It will take your mechanic about ten minutes to replace the driveshaft on a lift. Figure about twice that doing it in your driveway. No, you're not doomed. The front driveshaft can be rebuilt at any reputable driveline specialty shop for far less then a new Isuzu part. Just hit the yellow pages...Good luck!