PD 4786 was the designation of an Imperial Viper probe droid that was deployed over Ruusan in 5 ABY by Jerec.
Unlike other viper droids, this had not one, but four energy cannons, one at each compass point. It was equipped with Holocameras although at nighttime it operated with heat sensors. When attacking, sometimes it triggered a targeting laser.
It reached the planet one night when the network of sixteen smuggler-operated satellites were disabled.
Colonist Grif Grawley spotted it while looking for Bouncers with his electrobinoculars from Hill_461, but its heat signature and elevation indicated it was a droid and not a Bouncer. He attempted to disable it with his blast rifle but missed his first shot; the second slagged one of its sensors, when it retaliated, destroying part of his windshield; he dodged the speeder away from the second shot.
Eventually he destroyed the droid by remotely crashing his airspeeder into it. The droid remained in the same location trying to hit on the incoming speeder until they collided in an explosion. Grawley retrieved the probot's ID plate and brought it to the Smuggler's Rest tapcafe in an attempt to warn Fort Nowhere of the possibility of an impending Imperial attack.