Were is Argyle in Fallout 3

He is located in Rockopolis, which is an unmarked location. Go directly north from Girdershade, until you're directly West of Smith Casey's garage (your player, girdershade, and Smith Casey's Garage should form a 90 degree angle). It is hidden in rocks, marked by a banner of triangles similar to the ones found in Little Lamplight. Inside is a dead Argyle, and nearby is the unarmed bobblehead