The NEC ND3550A DVD burner was released by NEC in October 2005. The NEC ND3551 burner adds support for LabelFlash but both drives - together with the ND4550 and ND4551 - share the same hardware and only differ in firmware. However you should not try to simply flash a NEC 3551 firmware on a NEC 3550 drive or vice versa. This will NOT work.
CD Freaks published a detailled review of the Memorex 16x DDL-IN which is a NEC ND-3550A OEM drive.
Click here for detailed specifications of the NEC ND3550A and ND3551A.
The following firmwares are available for download here:
Overview on the used writing strategies