What does the drive identify itself as in device manager or Nero info tool or whatever you prefer for checking ID strings?
If it is identified as a Cendyne, you might still be able to tell by the firmware version, although if they changed the ID string they probably changed the fimware version too. But, if you can, try to match the firmware series against the firmware listed here to find the exact model:
http://www.jlms.com.tw/download.htm
Also, what are the physical dimensions? The 165H/166S models are shorter than the 163/163D models. You can see the specs here:
http://www.jlms.com.tw/jlms.htm
The 40x max CD-ROM read speed is suspicious since, as you say, LiteOn drives read up to 48x. Have you tested the CD-ROM read speed to see whether the 40x spec is a typo or for real? Maybe you don't have a LiteOn, if your drive really does max out at 40x.
If the drive is a LiteOn and made recently, it is probably a 166S.
Another thought - as you were handling the drive prior to and during installation, did you hear anything sounding like little ball bearings rolling around inside of it?
cfitz