Abstract: An adjustable mount for a laterally supported, rear view mirror which is attachable to a flat, upper surface of a side mirror support brace, said mount comprising an elongated base member having a substantially flat (i) top and (ii) bottom surface, (iii) opposing side walls extending downward along opposing side edges of the base member and opposing base member ends. The top surface of the base member has a closed configuration to conceal components and protect interior locking components against adverse elements. The bottom surface of the base member includes a pair of opposing flat shoulders which partially extend from the edges to an elongated slot. This elongated slot traverses the length of the base member and extends within its volumn to form a T-slot track guide which houses an elongated tracking member having a corresponding T shape.