[SHÖCK]

Of course it's a V3 gearbox, just like all AKs, AUGs, and Sig 552s. Why any stores would say it's a V2 is beyond me. That's good for you as the stock V3 mechbox will last instead of being worried about mechbox cracking with stock V2s. Good thing you are on a Canadian airsoft website. You see, because it's so impossible for us to import any guns (and even when we can, it costs 2-3 times as much as it does in the U.S.)...we spend all our time reading about guns intead of actually being able to just buy them LOL. So we are well researched.

V3 gearbox internals are all interchangable (aside from some bits on the outside like the selector plate, specific trigger assemblies, other doodads, etc.)

You can upgrade a G36 with the gears, cylinder, piston, piston head, spring guide, nozzle head, cutoff lever, etc. for an AK, and AUG, etc. but the nozzle is one part you need to get that is specific because each gun has a different hop-up/feeding configuration. I have interchanged parts from an AK kit into a G36 and back into an AUG before.

Your stock bushings should be fine. Yes, they should be 7mm and I believe STAR even has bearing bushings for one set of gears.