Merkava was designed uniquely for Israel. There is only one other tank that tried to do the same thing... well 3 if you count the M3 Grant.
The other i was thinking of was another experimental T72 tank that replaced the engine with a smaller one to allow a small group of soldiers aboard. The BMT 72 and BTMP 84 both unique Ukrainian experiments.
Like on the small cargo hold on Mi28 Havok Attack helicopters it’s an odd choice with advantages and trade offs.
The Merkava is the only tank that has the space. But it’s not really meant for infantry carry. The space is used primarily to hold the stowed ammo of the tank with about 10 ready rounds in the turret mounted semi automatic loader drum. If you emptied out the 48 stowed rounds you could squeeze in up to 8 soldier but at the cost of the ammo. Mostly it’s meant to pull a Merkava crew from a disabled vehicle aboard.
it trades off a number of things. The Merkava has a forward mounted engine like a APC or IFV. Now some claim that’s a survival advantage. Except not really. Because the engine is taking space that would normally be used for the composite armor. So the frontal hull armor is a little thinner than it should be and is more likely to get a mobility kill from a direct hit. This of course created the space in the back of the vehicle but it also increased the height of the tank. Which is fine for shooting down from a hill top not so for behind a berm. the front mounted engine also creates a oddity in balance. It’s front heavy. Most MBT are like supercars mid engine. The engine in the back stabilizes the vehicle it also means it’s easy to access and replace.
The advantage of the design I think comes more into play when the Israelis created the Namer. They had a easily converted Heavily armored IFV/APC waiting to go.
for them it made sense. But doing so on other tanks is problematic. The size and weight constraints and placement of the power pack make it more difficult. The BMT 72 had to have its infantry dismount on top of the tank. They fixed that with the BTMP84 but neither held more than 5 men.
