Patty Gurdy. I first heard her singing "Over The Hills and Far Away" and started listening to more of her stuff. I think this is a newer release from her:
Now playing ZZ Top - Tejas (original 1976 Terry Manning mix)
The later 1987 remaster is a great example that remastering doesn't automatically mean better. While the remaster sounds cleaner, the drums have a ton of low end thump and reverb added that sound like carp. The whole remix is a mess, for that matter.