Hi Joe,
The adjustable bars are shop made, they consist of two L shaped support legs with slots for attachment to the T-Track and adjustable horizontal bar. A horizontal beam is attached between the vertical support legs for stability and a thin moveable bar for vertical measurements. The measurements are based on the size of the board and model.
This is a photo of the plastic knobs I use in the track.
The link Zoltan posted will get you to the scales I just glue them to the vertical posts.
Mike