In 1990 I got my first Bell 47 ride at at Zemlock helicopter at Chino.
Following training in Maryland, I went back in 2000 after I retired for a week of brush-up flying.
At that time, he said he knew the guys that did the filming for the Film and TV series. It wasn't him or any of his 47D1s (H-13D/E) but he knew the guy and had photos from the filming.
If Zemlock is still in business, ask them.
BTW...what model of 47 does your friend have?
To be authentic, it needs to be a D, not a later G ...it's a pet peeve there are many wrong ones out there...even model companies (Revell for one) don't know the difference. The differences include cabin, tailboom, fuel tanks, skids (some variants) and stabilizer. In other words, pretty much the entire airframe.
A lot of otherwise knowledgeable airplane guys think Bells are like Model Ts or VW Beatles...that "they're all alike" (hint...VWs and Ts aren't all alike either).
Several months back I happened across an online ad offering a Bell said to have been used in the TV series opening. It was restored in military colors.
But the guy was
asking big (silly) money for it...something like $1.2 million or something.
A lot of money for a early '47...especially when you consider it as seen only in the opening and not used in a recurring role, like the machine used in
Airwolf or
Magnum P.I. (Magnum of course used several different 500s...all playing the same helicopter "character").