frame similarities

Good morning. I'm, once again, thinking of redoing my jeep once it cools off and am in research mode.

A guy on craigslist has what he calls a '70 cj5 frame but when you talk to him, he's not sure what it is. He sent me photos and it's definatley a willys frame but I can't see much of the front end. It's 2 hours away so I can't easily see it and he hasn't called me back yet.

The back end of mine is rotted off. If his isn't a cj5, how similiar would the back end be? He's asking less than what I can buy a rear cross member for online.

thanks in advance.