I know that with some time and a loupe I could answer my own challenge, but I thought it would make an interesting thread for those who know about Official Envelopes and those who don't.
War embossed (franked?) envelopes were issued between July 1, 1873 - July 5, 1884 along with all the other Official Departments.
As aside note the Official stamps were issued on the same date as the envelopes but were no longer issued in 1881.
Challenge is to ID which Scott #'s these three envelopes are.
Have fun and be informed