A seat assembly (22) for a chairlift or the like in which there is a transversely-extending hollow extruded body (31, 32, 33, 61, 62) having a length dimension sufficient to support a passenger thereon. A pair of side assemblies (34, 63) are mounted to opposite ends of the extruded hollow body, and an elongated transversely-extending securement rod (46, 47, 64) is coupled to both the side members (34, 63) and extends through the hollow body to sandwich the sides against the intermediate hollow body and secure the body members (31, 32, 33, 61, 62) together as a unit. The same system is used for forming the seat (23), as well as the seat back (24). Cushion attachment and tensioning recesses (81, 86, 91, 96) or pockets are provided in the extruded seat and seat back bodies which allow capture of enlarged edges (84, 88, 92, 98) of seat cushion material (85, 89) to effect attachment and tensioning.