Ok, thanks! I can scan the discs myself as I also own a DW1640. I just took out and already replaced the LG from the powermac with a Pio 110D without burning any disc with it, but may put it in and test it in another PC just to test it.
The LG GWA-4165B is a DL burner which writes 16x DVD+R/-R, 8x DVD+RW, 6x DVD-RW und 4x DVD+/-R DL, 40x CD-R and 32x CD-RW. According to this site (http://www.amug.org/amug-web/html/amug/reviews/articles/quad/) it can be flashed with Hitachi-LG DL04 firmware in order to write 3x DVD-RAM.
It is very likely that it is some other LG drive whose only name was changed in the firmware to be "fully supported by Apple's Apps". This is not unusual as Apple once before renamed the Pio 108 as Pio 117 in their earlier G5 powermacs.
For what it is worth this LG drive is "made in Japan".