I initially wrote Field Manual AU (Alternate Universe): 3028 starting in late 2011, with the first 'final' version going out on January 30th 2012.
I don't know how many revisions I have done to this document over the years, but it now barely resembles that original draft. An entire other document (FMAU: The Clans) was spun off and quite a number of things were changed.
I took inspirations for the universe from all over as I noted in the credits. Additionally great feedback from places like this helped me, I think, make the universe much better over time. Its still woefully full of holes but I'm proud of where its at and don't plan on going back and changing it now especially as I have built off of it so much.
Attached is the FMAU: 3028 Revised PDF with the latest fixes for typos, etc. I did just this week.
I initially re-wrote the sourcebook in early-mid 2016 (6/5/16 according to my notes). The format and layout (and a good amount of the writing) are taken from Field Manual Updates (one of my favorite BattleTech Sourcebooks of all time). I grabbed inspirations from newer and older texts for things like the CCAF redesign and a lot of Alternate Universe stuff inspired unit names, changes, etc. I also setup the Inner Sphere in about 3000 and played ISIF style for ~10 years with some buddies of mine to add some inspirations.