It's not in the Emhar kit, but I noticed pictures of Mark IV tanks which have a wedge-shaped panel with two sloped sides and two stright sides. The longer straight side sits atop the rear box just behind the small door on top, while the small straight side rests near the top of the rear panel. What is the plate's function, how is it attached, and did all or most Mark IV tanks have these?
Sounds to me like you mean the two panels of armour. I have attached a photo, taken from the Mark IV article on Landships, and with arrows added: are those the panels you mean, Long Tom?
If so, I believe their function was extra armour - the top panel protects the radiator, and the bottom panel protects the fuel tank.
Most, if not all, Mark IV tanks had the panels. The surviving tanks that you can see today that do not have them, used to have them but have lost them over the years either to rust (the one in APG) or rebuilds (the ones in Bovington, Museum of Lincolnshire Life, and Ashford). Grit in Australia still has them, and she never saw combat. As is always said, the one in Brussels is the most complete example, and is in the original colours.
If you are going to scratch build them, remember that the top panel did not obstruct the fuel tank filler nozzle that was located under the flap in the top surface of the fuel tank (thankfully, there are other photos that show the arrangement more clearly than my explanation!).
Yes, that was meant, though the tank in the USA has only the upper one and not the lower.
The tank in the USA used to have both plates, but it has been kept outdoors for over 90 years and the bottom plate has just rusted off. (As you can see in the attached photo.)
