Anyone who thinks battlemechs can't be modified, that those machines are stock-only and that variants are the only different chassis available, have never actually read a single fucking book or tro from the game. Or said people may be retarded. Like, actually, clinically, retarded.
OF FUCKING COURSE battlemechs can be customized, it's a core element of the game. If any of these shit kickers had ever opened a rulebook/tro, They would immediately find the build system. The tro's not only explained (and encouraged) customization, they flat-out told You You could even build an entire mech!
Listen fags, all of this "stock/variants only" shit is coming from the online pvp crowd that regularly get Their asses handed to Them in game, and instead of admitting They suck, They say it's the other guy's "OP" build.
The variants described in the tro's were examples. EXAMPLES. Any, and I mean ANY tabletop game's rulebook will be filled with examples of what the player can do with the game's character system.
Open up the rulebook for some faggy sword and magic game, and You'll find all sorts of fluff about characters. Like, maybe a little bit about some elf with a bad haircut who uses a staff and gets erections whenever they see the number five. That doesn't mean ALL elf characters MUST HAVE bad haircuts, staves, and a number fetish, it's just the game's writers' way of hinting at what You COULD do with the game.
Take the Catapult K2: The pult' is a missile mech, but to get the idea into the players heads that You can change things, there was a bit of fluff made about a variant used by the dracs' that had particle cannons on it.
Hell, read the fucking tros, and You'll find the variants were called "KNOWN variants". They would often state that there tons of customized mechs out there, but these EXAMPLES were some of the more popular ones.
And then there were the books. Most of these books described, in detail, battlemechs getting customized. And not just unit commanders either.
Nigger, the whole point of omnimechs were that they were EASIER to customize. The first wave of clan mechs all shared parts with one another, and clan tech was a Henry Ford wet dream of standardization. An omni with a damaged medium laser could have said weapon swapped for a replacement with little difficulty, where a battlemech would need to spend some time in a bay getting it's laser repaired, replaced with the same model, or go without until there was more time to jimmy rig something. A Timber wolf omni with a bad right leg could swap it's entire leg with one from a Mad dog, BECAUSE THEY USED THE SAME FUCKING LOWER BODY.
Archer Christifori. Canon. General in the fedcom civil war. Drove a Penetrator with CLAN er large lasers.
OF FUCKING COURSE You could mix tech. That was one of, if not the biggest motivation mercs had to fight the clans, to get some of that sweet, sweet tech. Risking Your shit against the clans and getting away with Their loot meant You could kick even more ass back in the Inner Sphere.
Motherfuckers, Battletech SET THE FUCKING MEME for customization. Look at any giant robot media from before btech. No customization. Now look at EVERYTHING after btech: The vary idea of a giant robot game without custom bits is considered an instant fail.
You're all a bunch of slack jawed faggots.