BAD, or Bingo Airsoft Designs, which is now the new name of Bingo Airsoftworks, shows how to install their F2000 Wolverine Hydra Engine Gearbox Replacement Kit... "This is the Bingo Airsoft Designs F2000 Hydra Engine Gearbox Replacement Kit. The HPA kit allows you to easily upgrade your G&G F2000 to use the Wolverine Hydra (w/F2000 nozzle). The kit includes everything needed to convert your F2000. You only need to hook it up to your air rig and tank and you are ready to go.