Dragon makes two kits that will build into UH-1Hs in 1/35. One is boxed as a Vietnam UH-1D and a German HEER UH-1D SAR model. Both have all the parts to build an H model, and then some.
The 1/35 long-body Huey kit was originally released by Panda, and reboxed by Dragon with new decals and PE. They are pretty nice, but can use some updates and TLC to make them look really good. Cobra Company has some great update / correction / detail sets for them.
UH-1D Vietnam
UH-1D HEER SAR
They also offer a USMC UH-1N
They can be found pretty readily on eBay, but I think they are currently (for now) out of production.
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