Have you seen the 1949 version I posted? It seems like most of the comments on this thread are about all the other versions. If Paramount later intended to keep the Alan Ladd version obscure in favor of the Robert Redford one, they’ve certainly succeeded.
I'm not into watching movies online, but from what I see of the 1949 version now, it may be a worthy, workmanlike effort. It's not quite the sensation the 1974 version was, though.
There was also a 2000 A&E TV version. I remember it with Paul Rudd as Gatsby, but he was Nick (which seems a lot more appropriate).