Quote Originally Posted by Dave Silcock View Post
Roger, that's exactly the point I was making, and having just put the rule book down there is no mention of period variations, neither does it come [T&C that is] under Schedule K. .
Have a look at the Manual (no.35) at page 486 and you will find :

“Period Variations” means variations carried out on that vehicle model, that were variations available in the era during which a vehicle model and/or its components were first used actively in motorsport competition, and