I remember seeing this when I was a kid in the early 80s. Pretty sure it was from the 60s. I remember it being in colour. Two young boys, one blonde, one dark haired (I think he was Mexican). Grew up together like brothers, grew old together. One plot point I remember is that the Mexican boy’s little sister was kidnapped by Indians. When they were adults, he finally found her. She was still living with the tribe, and happily married.