Pretty sure it was fitted to the last of the 79 model year Bays and carried on into the air-cooled T25/T3's. Mine is a very late '79 with a CU engine that has square ports on the heat exchangers whereas the early '79 models have oval ports on the heat exchangers?
are you able to enlighten us on Flywheels in any way, bit confused over here http://thelatebay.com/index.php?threads/what-the-difference-flywheels-clutches.37729/