You won't be disappointed. I called Chip today to thank him, and to ask him some questions about these barrels.
Chip, the Head Distiller for Balcones Distillery in Texas, is the one who posted about these being available for homebrewers on the AHA Forum. He said these were the sort of barrels he wished he could get his hands on when he was homebrewing.
There is a lot of information on one end that has clues about the prior contents, dates of emptying, and alcohol levels previously in the barrels. Mine say’s “Blue Corn” and what I think is an alcohol measurement (60.4% or something like that) and date, then “Malt”, another measurement and date, along with the dump date (early September).
So I am guessing that, along with the info on their website, that these held their “Baby Blue”, a Blue Corn Whisky, and then their single malt. Their website: http://www.balconesdistilling.com/