Here is what I know about Kahlua... Imported bottles were of usual bottle shape, such as yours. Bottles that were sold in Mexico were figural...kind of like a cross of a Budah and Aunt Jamima (now it could have been a special issue, but it was my only 'real' Mexican Kahlua so I'm just going off of that). As for age...I can't say. But they pretty much look like what you have there today, only difference is the cork top and not screw.
Now what I have mentioned is what I know from growing up and my Aunt bringing real Kahlua from Mexico for us (she went there a lot) It tasted different then what we buy at the store (better, actually) and the bottle was way different (not to mention that it was all in Spanish) To get a feel of the age, go visit their website, http://www.kahlua.com/main.aspx?language=en&country=usa&link=&recipe=&siteurl=
You want the Kahlua Culture button (they are kinda hard to read) and the first option should be time line. That was informative...but brows the 2nd button, which are print ads. Got to Past ads and see if you can find your bottle. That will give you a better feel of the age.
Thank you for the info, I did as you recommended and sent them an email seeking information about this Kahlua bottle. I dug up over a hundred bottles behind where my old barn was before the 1982 flood putting in a foundation for the new barn, that was in 1984 and I got a couple of bottle books but they weren`t much good as I only found one bottle in them. Almost all these bottles are pre-1900. Quite a few milk bottles and drug embossed bottles. Several I found in the attic hidden in the eaves were from GEORGE W WILLIAMS & CO HARTFORD CONN, DRUGGISTS. These bottles are perfect, but again can`t get any info on them. I figure someone in the house way back when was addicted and drank them in the attic and tossed them down the eaves. This house has a long and vibrant history, as it was built by a ship captain. I have the complete history from our historical society along with pictures. See the photo of the above Druggists bottle.
Again thanks for the help.