A mounting structure for mounting an automobile antenna, shaft, mirror or other device within a hole in a support surface such as a fender, at various angles to such support surface, comprises a base which partially passes through the hole, a device-supporting bushing which partially passes through the base, a clamping nut above, and a retainer below, the support surface. The bushing has engagement means above the support surface to mate with the clamping nut and stop means below the support surface against which the retainer pivots and bears. The base has a central aperture receiving the bushing, which can swing through various angles. A spherical upper bearing surface on the base mates with the clamping nut, and includes a flange bearing against the upper support surface. A toothed lower surface and a pair of legs extend downwardly from the base and have inner surfaces parallel to a given plane. Toothed upper edges on the plates on the retainer mate with the toothed base surface and a pivot point on the lower edge, thus engaging the bushing stop means.