In the 70's on HBO, there was a movie where the man and young girl rode threw indian country and then at the end they ride off in the sunset in a cadillac, what is the name of this movie?

Wanda Nevada starring Peter Fonda and Brooke Shields with a small role played by Peter Fonda's father, Henry Fonda. It is about a gambler who wins a young girl in a poker game and winds up going on a treasure hunt with her to the Grand Canyon. Two killers follow them and steal the gold from them, which may be cursed. Along the way the gambler and the girl confess that they love each other and the gambler seems to die to save the girl from the curse. She is going to be returned to the orphanage where she had been staying by the stern nuns who run it but it turns out that the gambler survived and he comes to her rescue and they drive off into the sunset. I hope this is what you were looking for.