Abstract: A guide block for use in an extendable tableslide mechanism of the type hng at least two adjacent slide members disposed on opposite sides of the guide block, comprising a first dovetail shaped projection having a first upper inclined surface, a first lower inclined surface, and a first side surface therebetween, and second dovetail shaped projection having second upper inclined surface, a second lower inclined surface, and a second side surface therebetween, wherein the first and second upper and lower inclined surfaces are inclined with respect to a horizontal plane at an angle and wherein the respective widths of the first upper and second lower inclined surfaces one greater than the width of the first lower and second upper inclined surfaces.