At least one probe droid was located in Pelvanida's control room. Admin Rudyard Shelton carved 'SOS' into its chassis and sent it across the desert to warn others that the base was being attacked, since the terrorists had blocked all outside electronic communications.
The probe droid was sand-colored so that it would blend in with the Nevadan Desert's surroundings. Other than this brief appearance, no other probe droids were ever seen or used. (Darwin's Soldiers)