2 3/8" X 2 7/8" (60mm X 73mm)

(front skirt) ISOREX

(rear skirt) 1042        

Picture courtesy Don Mecklenborg

2 3/8" X 2 7/8" (60mm X 73mm)

(front skirt) FOLEMBRAY

(rear skirt) No. 217           

Picture courtesy Tommy Bolack

2 1/2" X 2 3/4" (64mm X 70mm)

No markings 

Picture courtesy Bob Berry