I can only guess that they are for noise suppression - some local regulation maybe - I have never seen them either for real nor even in photographs.

Yes, maybe it's a Kiwi thing. There was sound deadening glued to the inside of the hinged metal panels also. The truck was assembled in Oz I think.

there should have been a water trap filter between the tank and the lift pump to start with if it is missing the one in the photograph will be an excellent choice

Does anyone recognise this gearbox on a 466 Bedford? It's described as a 4-speed but it looks nothing like the TMC gearboxes that I have seen on TKs