On the back of a "Late" Tiger you will find a small oval port cover (circled). This didn't exist in "Early" or "Mid" Tigers. It is present in Trumpeter's kit.
The port (arrowed) gave access to a heater system in the tank's engine compartment. This comprised a few tubes and connections to the water pipes, plus a tall flat chimney.
Despite having the port cover, and the relevant hole in the real wall, Trumpeter's kit does not provide any of the heater system. It is interesting that Rye Field's smaller 1/35 kit has it.