About this detail of the Tiger
The new Tiger 1 kit from Dragon includes the four fans that pulled air through the radiators. They can be seen through the rear deck grilles. The grilles in the Dragon kit are separate parts and can be posed open. This was done only for maintenance of the fans; it was not necessary during submersion of the vehicle, when the snorkel was installed.
This photograph shows the fans installed in the Bovington vehicle after restoration. The fan blades are a 'white metal' colour; the central disc is a bronze colour. The round ducts containing the fans are also white metal.
The fans are surrounded by a blanking plate that prevents air flowing back past them. The plate is thin sheet metal with felt or fabric on the edges. It has holes for small screws around the openings; they could be added as detail to your Dragon kit. Notice in the first image that the brown sealing felt can be seen around the edges.
This photo shows a very rusty old set of blades. Note that they have the profile of an aeroplane wing, with the trailing edge away from the radiator. Seen from above, they turn anticlockwise.
In the Bovington vehicle, the entire compartment and blanking plate were painted in the standard interior blue/green colour. For a late Tiger, the hull sides may be primer, but the plate and other separate drive components were probably still painted blue/green.
Another view of the Bovington fans. One of the water pipes from the radiator can be seen above the fans; this is not provided in the Dragon kit because it is never visible.
The walls of this compartment above the fans were bare in most Tigers. But some vehicles had S-mine launchers at the rear corners, and the electric trigger wire for the launcher went along the inside of the hull wall. A hook for this wire was visible just above the fans, screwed to a small block welded on the wall. The wire exited the compartment at the corner, through a tiny notch in the grille plate.
[1] Survey of Tiger 250122, at Bovington museum, by David Byrden