But seriously, folks, here's a lil' more 'splainin' 'bout that ther' tank and what she does, and what'en I be doin' inside yadda yadda yadda. There are four positions in a tank, Driver, Gunner, Loader, and Commander.

Driver
Pshuto k'mashma'oh, the Driver makes the tank go. He learns how to move the tank over such dangerous obstacles as sand dunes, other sand dunes, and even BIGGER sand dunes. In advanced driving, these nuggets learn how to handle bumpy things like boulders and four-door sedans, and lumpy things, like small (and large) furry woodland creatures, or people. In super duper advanced driving, they learn Night Driving, Biggest Sand Dune Ever Driving, and ReMix/Techno Driving.

Drivers often get a bad back and knees from the intense pressure required to break the behemoth. They also get the most and best sleep when you do tank-stakeouts.

Gunner
Gunners are the raison d'etre of the tank. They blow things up, the perverse extreme of the secret fantastic fascination Man has with fire -- or the fascination Little Boys have with fire, for that matter. Therefore, Gunners have to memorize emails and emails worth of information on the speed, weight, and firing of the various shells, the effects of weather conditions, and how to toggle, er, toggles. Gunners have the most toggles out of anyone in the tank. I mean, they're drowning in the darn things.

Independant of the tank model [Merkava Mk II, Mk III, or Mk IV], Gunners have oodles of fun, since they shoot the big gun at destructable things. The more advanced the tank, the more closely the cannon, machine guns, laser targeting systems, distance estimators, and buttons and widgets resemble a 10 year old's birthday present; a ten year old, I might add, whose agnostic attitude towards the tooth fairy has convinced him of the existence of Aliens from the Future with great big ships that deal electronic death to their puny enemies and whom, amongst other things, exchange human teeth for US currency.

Loader
The Loader, much like the pancreas, is a crucially important, honorable, and demanding job that just sounds very uncool at cocktail parties ("Hey, babe, I'm a pancreas." Suave, real suave...).

The Loader, whose official job title is Loader/Radio Operator [or Armer/Radioer, or Armamentor/Radiotor, ad naseum... ta'an/qashar], is the tiger in your tank, performing various miscellaneous jobs that are the speed-bottleneck of effecient operations. He must be fast! In the final analysis, firing takes a second, and driving as well involves the instant reactions of the driver, however sluggish a 60-ton hunka hunka burning steel might react (like a [real] football linebacker -- built, but a bit slow). But rearming the tank to fire again, or servicing any of the many weapons that might jam takes a special kind of motivated effort.

The Loader rearms the main weapon for every shot, choosing what kind of shell to load [anti-armor, anti-personnel, or a special shell that does a mediocre job against either]. From carrying all these shells, Loaders get big biceps, flex flex, and can hurt their back. Luck favors their dice ['The Lord smiles upon their lot'?] in that they get their own hatch on top of the tank, and so experience things that civilians take for granted, like the Sun, or fresh air, unlike the mole-like myopic life of a Gunner or Driver (who can't hear normal things, for that matter, being next to the engine), buried as they are within the belly of the beast.

THE FOLLOWING SECTION IS RATED NP-45,
AND IS NOT SUITABLE FOR PARENT-READERS OVER THE AGE OF 45 WITHOUT A SEDATIVE
The most important job of the Loader, all agree, is nevertheless to Not Die. Not dying comprises a good chunk of Loader-training, much of which consists of shouting at us. The versatility and flexibility of the Loader's various jobs is a trait also shared by the various and flexible ways of Dying, which can be accomplished successfully in many ways.
1) The swivelling multi-ton turret could snap off many a life or limb and not even the commander next to you would notice amidst all the noise and hubbub, so get verbal confirmation from him so that he knows what you're up to!
2) The recoil from the main cannon extends the diameter of the entire turret, with an impulse of about 70 tons*sec. So if the Gunner errs...
3) The tank could flip, leaving the Driver and Gunner relatively safe, if bruised, but the Loader peeking out from his pretty hatch would suddenly find a tank on top of him (this also applies to the Commander, but see #1 and #2).
4) Also because of the hatch, the Loader is exposed to enemy fire when groundhogging [or even praerie dogging] out of his hatch, say, to fire his [very cool] machine gun, or lob a grenade over the side. #4a, don't drop that grenade! Oh, and #4b, shrapnel.

Commander
Gets all the honies. No, seriously, he has override controls over the entire tank, and if they put some female chauvinists in this position, they could probably multi-task the entire tank. Simply put, Driver + Gunner + Loader + minor Tank Mechanic + more Infantry training = Tank Commander.

However, there is the sense out there that the Loader is some guy who, in a very cool, professionally manly fashion, slaps a magazine into his assault rifle, cocks the weapon with a sharp mettalic chk'chik, pronounces for his audience at home, "Locked and loaded," and then...gives the gun to somebody else who goes on a wild shooting spree [for the squeamish, think paintballs], and then comes back to have his gun reloaded, rinse and repeat. But is completely not true. We also work the radio!