When metabox went out of business OWC bought and sold the rest of their stock of accelerators: http://eshop.macsales.com/Accelerators/Vendor_Page.cfm?vendor=metabox

I would suggest asking someone at owc...

Also: here's some information about the Joecard z: http://www.xlr8yourmac.com/G4CARDS/MetaboxG4_450_2MB/index.html