 Toyota's GT-Four / All-Trac system was originally released on the ST165 chassis Celica that was only available in Japan.The system used a locking transfer case that was the same as the electric/vacuum system that is found on U.S. All-Trac Camrys.For the 1988 model year when the U.S. All-trac system arrival, the Celica GT-Four / All-Trac had changed the transfer case to a viscous coupling unit.