rear axle

Hello! I think I found what I need but I was hoping someone could shed some insight before i purchased. I have a 2000 GMC jimmy in which I am trying to swap the rear end on. I bought the rear end off a 1998 Jimmy not knowing there was a lenght difference in the axel. So now I have a axel that is...

The diff. in my Suburban is shot. It seems that replacing the entire rear axle assembly will be less costly than fixing or buying another diff. itself. I found a rear axle online and I was just wondering if anyone had an opinion in regards to the credibility of the source I have attached...