Have you measured your track? It may be that Garhauer's current options won't fit your track properly even though they made the block on your current car. My 1980 Oday 25 had all Schaffer blocks and track. I forget if the track was slightly smaller than 1" or thinner than Garhauer's track. I tried a Garhauer low lead car on my genoa track of the 25. It worked for what I wanted, a fairlead for the furling line, but it was too loose to use as a genoa car.
That's probably why they referred you to D&R.