An anchorage device including a molded anchor base piece (14) received in an oblong hole (30) punched into an automotive body panel and secured by mating of grooves (42) formed in the periphery of a plug portion (24) of the anchor base piece adjacent a flange portion positioned against the body panel portions adjacent the hole. The complementarily shaped plug portion (24) is inserted into the hole (30) with a seal (32) compressed beneath the flange (28), and rotated to cause the edges of the body panel to enter the locking grooves (42), forming a fluid tight seal to the body panel. The base is formed with a keying bore (44) or other anchoring feature to which a mating fitting may be readily secured.
