Here's why:
* Different Body Styles: The Rubicon is a trim level, not a specific body style. While both Rubicons and regular Wranglers can come with hardtops, the Unlimited body style (the longer 4-door Wrangler) has a longer wheelbase and wider body than the standard 2-door Wrangler.
* Hardtop Compatibility: Hardtops are designed to fit specific body styles. A Rubicon hardtop for a 2-door Wrangler will not fit on a 4-door Unlimited, and vice versa.
To find a compatible hardtop for your 2006 Wrangler Unlimited, you'll need to search for a hardtop specifically designed for a 2006-2007 Wrangler Unlimited.