The G&G m14 gear box has 7mm plastic bushing, I upgraded mine with 7mm guarder bearing and Prometheus 130 spring, The G&G gear suck they are weak link, They will handle the stock spring but with anything upgraded beyond 110 they will fail,
Good news is they are the same as Systema and Other well know makes, I would suggest toque ups
Yes, JT phoenix has a set or two on there shelves right now
Yes to answer your qusetion YES they Version 2 and Three will work
Now the TM 14 gears are smaller in size,