Chef, this is a bit confusing. There are two kinds of OEM here :
1. The drive came installed in a system you bought from a company like Dell - this is the kind that is usually a non-GSA drive. (that isn't completely true either because some HP systems come loaded with a GSA-4166B).
2. Rebadging - where one company gets LG to make drives for them, and then they sell them under their own brand (e.g. Buffalo, IO-Data).
The "OEM" referred to above is type 2. However, things get even more confusing at this point :
Hitachi releases their own versions of LG writers, which tend to be slightly different. In the case of the 4167B, Hitachi's version a)has a black casing (LG's is silver), b)uses different firmware which gives it UDMA4 (LG's is only UDMA2), c)auto booktyping, d)is made in a totally different factory in Malaysia (LG's is made in China). These are typically only sold in Japan and rebadged as some other brand name. Yet Hitachi's versions have exactly the same model numbers as LG's versions.
The 4163B mentioned above is a rebadged Hitachi 4163B sold as an NEC with different firmware.