Hi Guys,
I've added a "Period" heading to our 2017 regulations for non-IROC classes which clarifies the time period that eligible cars were raced for the various classes. For example, GT and Restricted GT cars must have been produced from 1976 onwards. You can check out the eligible periods for each class in the 2017 Regulations.
This should further help clear up any ambiguities you may have regarding which cars are eligible for each class.
Gordon