below the horizontal relative to the connector coupling assembly 28 is prevented by fixed pin 41 in order to avoid improper placement diagonal 26 is connected to the swivel base 22 and to the foot of a scaffold post 32 which includes its associated screw leg 52 through a clevis 54 carried on the swivel base 22 in the embodiment depicted in fig1 swivel base clevis 54 is substantially the same as connector clevis 40 and is positioned on the opposite end of adjustable diagonal 26 diagonal screw 47 is demountably maintained within socket 56 by means of hinge pin 58 the hinge pins 46 58 permit different size diagonals 26 to be readily substituted in a given scaffolding assembly 20 and thus allow for interchangeability and ease of construction and installation swivel base 22 is optionally provided with a base pad 60 interposed between the base plate 61 of swivel base 22 and the sloping boiler wall 24 this base pad 60 provides a cushion for the base and avoids damage or scarring of the boiler wall this base pad 60 may be formed of any suitable material including plywood or neoprene clevis 54 and screw leg 52 are both pivotally connected to base 22 through bolt 62 this advantageous arrangement provides for a more direct transferral of the horizontal component of that portion of the weight of the scaffolding latticework 63 borne by screw leg 52 into the inner scaffolding supports.