Looking at the Web site pictures of the types of drive bays fitted in the Sonata range, they appear to have rubber silicone plug style 'feet' / grommets. If so, dosen't your existing IDE Drives bolt/screw into those .i.e. screw fitted from underneath rather than side bolt/screw mount?
The website picture below shows a slide tray that can also be fitted in the Solo unit as an option, but that also uses the silicon plug 'feet' / grommet mounts:
http://www.antec.com/images/product_detail/SOLO/Big/3.jpg
An installation manual for the Sonata SOLO II unit is also available from this link (see page 16, comes with silicone grommets as standard):
http://www.antec.com/pdf/manuals/SOLO_II_Manual_EN.pdf
If the grommet feet are missing spares are available here, (if Antec ship to uk):
http://store.antec.com/Product/accessory-spare_parts/rubber-grommets-harddrive-p180/0-761345-30242-5.aspx