what transmission where you planning on with the 4.3L? doesn't matter, the answer is no. An isuzu tcase is not going to bolt to any trans behind a 4.3. First off, if your isuzu is a manual, then your tcase is integrated into the tranny. The automatic isuzu's do have detachable tcases, but doubtful this will go to any 4.3L tranny without tons of work (ie not worth it).

If you're able to get a 4.3L/tranny/tcase in your Isuzu, then driveshafts are going to be the least of your problems.

-Rob