Abstract: A side mounted rear view mirror head assembly for trucks includes a mirror head formed with a sheet metal back or cover and a mirror, enclosed between a pair of end caps, in which an intergral extended portion of the end caps define lateral slots providing for corresponding lateral adjusting movement of a mirror head on a generally U-shaped support arm. The mirror head itself includes a square tie bar which extends between the end caps and is fitted into tie bar engaging bosses in the end caps, to resist twisting of one end cap with respect to the other, and to stiffen the mirror head.