Hello Terry,
I didn't find a manual yet but I did find a site (zzounds.com) that said the CD-Rack comes with a C50 SCSI cable.
Here's a picture of a C50 cable.
http://www.cablestogo.com/product.asp?cat%5Fid=1306&sku=28060
Do those connectors look like what's on the back of your units?
Once in a while you'll run into a sites that sell stuff and include the manauls in .pdf form.
You might be surfin' for a while...
Or you could call Roland's Product Support department at 323-890-3741.
Hope this helps.
mike