As Gino stated that most if not all 1/48th UH-1D's are OOP. That’s not to say you still can't get one. The one's to look out for are from Esci, Italeri, Revell and AMT. The AMT kit is much better, cleaner and better detail./ They still can be found on Ebay from time to time. As for the marking, well I'm sure it not all that had to make yourself on your computer and print at home or take to a local print shop to have them do for you on clear decal paper. As for a color match from Tamiya, well after looking at many on-line photos I concluded, in my own opinion, that is was a cross between Tamiya’s Neutral Grey XF-53 and Tamiya’s Dark Grey XF-24 that seem to be the closest. I’d say play between to two, mix some here a bit here to get a close match. A last resort would be is to get the new Teastors metal model UH-1D, take it apart and redo it in the new color and markings.
Not sure if you shop eBay but here is a link to a few UH-1D’s…
Models Joe