LSD Tranny

Does anybody know how to identify a GSR LSD transmission other than the LSD that's normally stamped on the housing? Is there ever a time when the LSD is not written on the housing? The reason I'm asking is because just this morning I went to a shop to buy a motor and LSD tranny but I didn't see the LSD stamp in clear view but the shop owner told me that it is a LSD transmission. Maybe it's written on the bottom. Can someone please help. Thanks.