Thread type for original fuel tank

[Marty McOmber]

Hey all, 

We have a 1984 Passport 40 and, long story short, I'm finally getting around to replacing the old copper tube fuel lines with modern A1 fuel lines. That means changing the 90 degree elbow fittings on the tank (which has 45 degree compression fittings for the fuel line connector).  

Does anyone know the thread type they used for our tanks of that era? After much trial and error, I believe they are either BSPT (British Standard Pipe Tapered) or, more likely, BSPP (British Standard Pipe Parallel).  I know that NPT (National Pipe Thread) does not work, nor any of the American parallel standards. Google's AI helpfully confirmed that Taiwan uses BSP standards pretty commonly. 

Thanks for helping nail this down. 

Cheers,

Marty McOmber

206-335-9263