Here are the 3.5 -> 2.5 adapters. They work with my supermicro 486 case.
9W8C4 Y004G 3.5" to 2.5" Adapter for Dell F238F R730 R720 SAS/SATA Tray Caddy 711765390779 | eBay
9W8C4 Y004G 3.5" to 2.5" Adapter for Dell F238F R730 R720 SAS/SATA Tray Caddy 711765390779 | eBay