you are AVed, please use the AVed section if you are going to ask about getting parts. you should have access to the classifieds section, where there are a few items you are looking for already posted.
as far as your gearbox goes, if it's metal it should do fine, but being G&G you may want to look at upgrading your gears.
Weapons Technician / Gunsmith
Don't look at me, I don't know, lol ¯\(°_o)/¯.