I have uploaded a H.264, 16:9 (720x480, total 120mb) at bitrate of 1800, 24F.
The result is a stretch 4:3, what am I doing wrong?

My goal is best quality possible in SD. Can you help?

720x480 is not 16:9. Nor is it a square pixel format. I'm betting that's where the wheels are falling off the wagon.

720x480 is not 16:9. Nor is it a square pixel format. I'm betting that's where the wheels are falling off the wagon.

Render out at 854x480, with square pixels before uploading to YouTube.

720x480 anamorphic (at 1.2) should work, but you're having trouble with that, and it's usually easier to render with square pixels anyway.

Thanks guys, I will try and let you know.