Macintouch.com said:
ATA:
ATA Bus:
SONY DVD RW DW-D150A:
Model: SONY DVD RW DW-D150A
Revision: 1.MD
Detachable Drive: No
Protocol: ATAPI
Unit Number: 0
Socket Type: Internal
Low Power Polling: No
...that's the supplied drive, a fairly typical one. Unless there's something REALLY special about yours, I don't see why it wouldn't fit. Take out the carrier from the Mac Pro, and see if it fits. No harm done.
Apple also has a manual up in their support section for the installation (DIY) of a new/replacement optical drive. It doesn't mention removing the front piece of the trays, so I assume it's written only for their supplied drives, but you will need to take off the fascia (an easy task) in order that the tray fit through the slots on the Mac Pro.