I would check with ZEPHYR Spars ,a Division of Cape Cod Shipbuilding i nWareham, MA. They made spars for some of the early O'DAY models and still are a class-approved source for the Rhodes 19 spars.
That said, check the Day Sailer Class Association web site (
www.daysailer.org) for the forums, later years of the DS did not have the jumper spreaders and I wonder if any racers have removed them..... (if Class Rules allow). Otherwise, someone there may have a different source besides Zephyr.
http://www.capecodshipbuilding.com/site/aboutzephyr.php
For those not familar with jumper spreaders, I have added a few pics. They basically control mast bend by stiffening the part of the mast above the point where the shrouds and forestay attach. We had them on our old CAL 21, which basically has the same mast as the CAL 20.