we are redesigning our webbased software product. All main tabs (called: modules) have the same layout: In the upperleft of each they have a breadcrumb and the page title.
Most modules have a second navigation level, represented by a second horizontal tabbar as shown in wireframe A
Our configuration Module also has two levels, but here the second level has just too many pages for a horizontal tabbar.
Vertical tabs could be a very good sollution. See wireframe B.
However, the vertical tabs make the title and breadcrumb shift to he right. that doesn't feel too consistent to me! Because of this, I prefer to place the vertical tabs on the right of the page. Wireframe C
Is placement of vertical tabs on the right side wrong or 'not done'? Does anyone have some insights about this?

download bmml source – Wireframes created with Balsamiq Mockups
