I was searching for a 6" rudder extension from Top Secret boats.
Then I called the number on the web site only to wake up an elderly lady that was not happy.. lmao

I just searched the new Jim's r/c Boat Dock and found topsecretboats as a member.He was on there before it went down selling parts.You could contact him from JRCBD.

He closed down the RC boat business and was trying to sell that part off. He was unloading the rest of his inventory on eBay but it's probably all gone by now.
He had a military contract that was taking up more of his time and was a bigger moneymaker so something had to go.
Too bad to find out now as I sold a boat that had just what you needed on it.

You can use speed master 5" stand offs

Top Secret boats was just on Jim's Boat Dock and said he still has few 6" rudder kits laying around

Thanks I posted a reply and a pm.