This photo shows the air cleaner box and the 3.5 inch flexible hose coupling it to the air cleaner. This hose was in poor condition, and finding a suitable replacement proved to be quite a challenge. Plenty of sources for 3 inch and 4 inch hose sections, but 3.5 inch takes some looking. Eventually, we got a suitable hose from Lotus Cortina Spares Centre, Ltd. shown below.