First off here's a 1/35th main rotor transmission for the Italeri and Academy Blackhawk kits.
If in the past you had the chance to build one then you know that all you get in the kit is nothing but a thimble.
Now I will say that it's not all that accurate BUT it is close and looks tons better than the kit piece. I made up this part by looking over photos of the internet.
You'll notice that the bottom side is keyed to fit part A3 (photo)
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To purchase them contact...
Section 8 Hobbies
FAB Resinworks
2243 Seneca St.
Buffalo, NY 14210
716-828-1102