Are there any numbers or symbols on the bottom? If so, post a picture or just indicate what they are and that would be a good place to start as far as year goes. Also, is there any embossed message that states something to the effect "Federal government forbids the re-use or sale of this bottle"?
If logueb is correct in his year prediction, the bottles should be stamped with the Federal warning somewhere on the decanters. If not, there are post 1964. Again, if there are any numbers or symbols on the bottom, posting them would help. Doesn't have to be a pic, just describe. Just trying to help.
Post note: Could you get a close up shot of the red label at the bottom of the first bottle? It looks like these bottles come from South Africa and were imported to the States. Is this correct? Does the second bottle have the same red label toward the bottom, rear? If from South Africa, they won't have the Federal warning I cited (at least I think that's true for imported spirits during the post-prohibition era).