Hello jason. I have been doing Gallegos research for several years. My Gallegos ancestors returned to New Mexico in 1693 after the Pueblo Indian Uprising of 1680.
My family line probably started in the New World in the Poanes Valley (modern day Durango, Durango, MEX. This where the father of KLuis gallegos Terrazas de Gallegos was born. his father is thought to have been Juan Borruel, from the old Spanish kingdon of Aragon. Juan Borruel was perhaps a soldier in the army of Francisco de Ibarra, governor of Durango and Nueva Galicia. It may be that your gradfather's lines descended from Juan Borruel. It's difficult to say.
I have lived in the Rancho Cucamonga area for many years. I am published in the New Mexico Genealogist.
If I can be of assistance in your research please drop me a line at email@example.com, or you can call me at (909) 980-2113.