https://triggerairsoft.com/shop/QD-T...-Shell-V3.html
I bought the above gearbox to give me easier FPS flexibility for my G&G RK104 EVO. I actually ordered the microswitch version but was sent the mechanical trigger version instead. (Trigger made good on a refund). No idea on OEM btw.
Out of the box, it's a good looking gearbox. It doesn't come with a motor cage so be aware of that. (It becomes and issue in a bit here). The first issue I found was the coating was partially covering a few of the bushing holes so I had to file those a bit.
Internally, the wiring, trigger and cutoff lever are all good quality. No complaints.
I installed lonex steel 8mm bushings along with SHS 16:1 gears and high torque motor. Here is where the fun begins.
My G&G motor cage was a loose fit on the gearbox. There was a 1-2 mm gap between the top of the cage and the bottom of the gearbox. This allowed forward and back and side to side play. I figured the pistol grip would stabilize it. After some testing of my shim job, I noticed that the gear noise was smooth to noisy depending on what exact angle the cage was sitting. So I asked another tech on my team to take a look at it. While he was testing, he reported a high pitched screech had developed. He tried other brand motor cages and all had the same issue with the gap.
When I got it back I opened it up and after some investigation, found that the bevel gear bushing was now not holding the bevel gear solidly. When I spun the bevel gear, I got the same type of noise. Best that I can tell is that the sloppy cage had put uneven pressure on the bevel gear and had actually worn an oval into the bushing.
I replaced with new bearings and the noise went away. I ended up shimming the space between the gearbox and the cage with layers of gaffers tape and it is now rock solid. The jury is still out on long term function.
Moral of the story? The gearbox is well built, strong and looks good. But buyer beware that the cage connection point seems off spec - at least from the several brands of motor cage that we tested.