Yeah, I know what you mean. There is one bloodline of mustangs, I can't remember where they are, that were fairly isolated and were from the Spanish bloodlines. They are really gorgeous!
I know that there's one 'strain' of mustang blood has one less spinal vertebrae than the others.
Not too long ago, I happened to stumble across an article that discussed the BLM management of the mustang herds.
Most people, (like me) think(thought) that the BLM was gathering/managing those horses for the 'good' of the herds.(to keep them from over populating/starving)
But the average size of those herds are 75-80 head...per hundreds/thousands of acres.