The Karmann T bodies were built lighter, and that is why the T/Rs were built with T VINs I think. Another reason may be that the Ts were homologated with the lightest weight prior to 1970, and to use an S would have required items to be removed to fit homologation rules, and that may have made it difficult to get past FIA inspectors. Were all the T/Rs built by the factory?
Gib