Was going to put an hpa engine in the gun. Had it working but not tuned then decided to go with a different body. A lot of permanent modifications were made such as the gearbox rear half was chopped and a buffer tube was threaded into the lower receiver. The upper has a small stress crack in the side when I removed a rail but doesnt effect performance. A few peices are missing like the barrel and hopup. I'm probably missing a few other things as well. I replaced the selector with a standard selector switch. The original selector switch is in the bag of parts. If you are looking for a specific part just reach out and ask me.