Carrol,

Here's all the info on the Blessington Book.
Blessington, Joseph Palmer " The Campaigns of Walker's Texas Division ( New York : Lange , Little & Co , 1875)
[ reprinted ( Austin : State House Press 1994)

I'll keep looking for others ; however, this is a great place to start. I believe it is still in print , so you can probably buy it on line or get one of the big book houses to order it for you. Your're correct, checking on your gggranddad's muster cards is a good idea. Also try the website for the National Park Service's lisiting of Civil War soldiers , sailors and cavalrymen. Good luck to you. Holler if I can help. Best Regards, Craig Morin