XTRO Primitives and TRO 3075 describe a series of Merkava upgrades that kept the venerable tank in service from the days of the Terran Alliance all the way to the end of the Reunification War. Of these, we only get full specifications for the Mk. VI (XTRO) and the Mk. VIII (TRO 3075), though the Mk. VII is pretty well described and an introduction date for the Mk. II is mentioned. So, I wondered what did these earlier designs might have looked like and my brain got to work.
I started with the Mk. II, as it's introduction date is listed as 2294. We don't know if the hypothetical Mk. I is in an any way related to the modern day Merkava but, whatever this "original" Merkava looked like, it exists in a time prior to any playable era of Battletech.
It seems likely that the weapons of the previous versions established the pattern that we see with the Mk. VI and Mk. VIII. That pattern being a main gun, supported with missiles and machine guns. But in 2294, we don't even have prototype LRMs or SRMs available, but we do have rocket launchers. Also, for the main gun, the AC/5 is available but there is a better choice. In an era when BAR 7 armor is the best available (and BAR 6 is the best that is widely available), the Heavy Rifle is clearly superior to the AC/5. The Heavy Rifle does nearly twice the damage, can breach any armor and it's only disadvantage is heavier ammo. So, the Mk. II might have looked something like this:
Merkava Mk. II Heavy Tank
Producer/Site: Leopard Armor, Terra
Developing Engineer: Unknown
Introduction Date: 2294
Non-Production Equipment Analysis:
Primitive Combat Vehicle
Primitive Rocket Launcher
Technology Base: Inner Sphere (Primitive)
Movement Type: Tracked (Medium)
Mass: 75 tons
Equipment Rating: C/C-X-X-X
BV: 415
Cost (C-bill equivalent): 741,563
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Equipment Type Mass
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Chassis/Controls: 13.0
Engine/Trans: ICE 39.0
Cruise MP: 4
Flank MP: 6
Fuel: 512 km 2.0
Heat Sinks: 0 0.0
Power Amplifier: 0.0
Turret: 1.5
Armor Factor (BAR 6): 83 4.0
Internal Armor
Structure Factor
Front 8 18
R/L Side 8/8 16/16
Rear 8 15
Turret 8 18
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Weapons & Equipment Location Mass
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1 Heavy Rifle Turret 8.0
2 Primitive RL 15 Turret 2.0
1 Machine Gun Turret 0.5
1 Machine Gun Front 0.5
Ammo (Heavy Rifle) 18 Body 3.0
Ammo (Machine Gun) 100 Body 0.5
Basic Fire Control Body 1.0
Crew: 7 (1 officer, 2 enlisted, 4 gunners)
Cargo: None
Notes: None