I wonder if it was a convertible-only difference or just an early vs. late seat belt difference? I can't tell for sure, but it looks like the buckles in the console insert do not appear to be the 67 style buckles on #99. I should have pulled one out and got a better photo of it and also the insert on the shoulder harness to see what style it was. I am invited back so I can check next time. The guy had some amazing original cars in his collection.
When I spoke to Stuart about this 2 years ago, he didn't think any came this way.