1968 firewall to fender supports

I'm an original appearance guy and I'm trying to determine whether the diagonal firewall-to-fender braces above the engine were factory-installed on all Deville Convertibles. I've owned two '68s and neither had the braces... both have mounting points on the firewall and plugs on the wheel wells, but no braces. I would think a convertible would need them even more than a hardtop. Checked all my factory literature and nothin..

I know these are removed often, but I've only seen one convertible that had em out of dozens. Surely EVERYONE didn't throw them out...

With 'em (ebay listing, a Sedan Deville)...


Without 'em (another ebay car, this one's a convertible)...