Asaki said:

I've seen one on YouTube of someone modelling the all-white prototype, if that's what you mean. I think that was for the movies, though, and not the special.

none, thank you for the link.

I've never seen this, and it's fascinating. I believe it, but at the same time it could almost be a private joke by Ben Burtt and Duwayne Dunham, to see just how gullible we all are.

It probably WAS from after the Holiday Special, but it's still definitely at the level (as Burtt says) of prototype.

Thank you both!