Scott states the following about the 1875 reprints (which includes #104)
Quote:
These stamps can be distinguished from the 1861-66 issue by the brighter colors, the sharper proof-like impressions and the paper which is very white instead of yellowish.
The reason for the sharper impressions was that new plates were made for these special-printings. As such, the stamps really stand out!
Your stamp is a 68.
Cheers!
Brian