The oldest paperwork we have for Fleetwood caravans is 1980, this mentions "B & B Steel Chassis with Auto Sigma Reverse Hitch" as being part of Colchester's standard equipment
The Colchester De Luxe range for the same year, however, was "built on a new Al-Ko chassis which saves weight due to its unusual design", according to the Caravan Club article Fleet of foot which you can read under Fleetwood Articles.
Note: We've read on the internet that B&B were taken over by Al-ko in 1982 and the B&B chassis was no longer used, by caravan manufacturers, after 82/83 in favour of the new lightweight Al-Ko type chassis.
