I'm not sure exactly which models had these longer pipes, but I can say for sure the MY89 with Grundy system DOESN'T - Hence why I don't need.
They are stainless steel ( I painted with a heat resistant black paint) and the flange plates are full thickness.
Photo above shows the shorter (MY89 Grundy) just for comparison.
Also have the shorter Y piece which I think may be the correct Y for these. Flange plates are good, but there is a repair along one edge.