If your transfer case does not have a locking central differential, the truck won't move without the front driveshaft.
Your '99 may or may not
No, it will not damage anything to drive without your front driveshaft while yours is being rebuilt. My wife drove hers for several months without a front driveshaft.
Yes, I am still alive, and still in the Rover parts business.
Text me for greatest likelihood of finding me.
Dominic Perodeau/Global British is a thieving bastard, do not send him money.