A quick learner from Rural Hall, NC says:
February 2, 2012
How thick is the 23-204? The guide that was installed when the house was built is made of a fairly thin metal plate, with the outer guide being adjustable. I have never seen one like it before.
Tom from SWISCO responded:
February 3, 2012
Thank you for posting. The thickness of the center plate of the 23-204 Adjustable Floor Guide is 3/16", while the thickness of the two outer, adjustable plates are 1/8".
If you were to upload a picture of your original hardware, we may be able to identify it for you, or at the very least tell you if it's still manufactured.