I have recently rebuilt a Broken Innova that I acquired and as it had the silencer adaptor but no silencer I purchased a male fitting 1/2" UNF Silencer.

I does not fit - wrong thread

My other Innova that has the original adaptor and silencer is at my secure lock-up and I can't get there for a few days so I can't make a comparison

I have always taken it for granted that these old aftermarket adaptore were 1/2" UNF

My Question is - what is the thread on the old aluminium silencer adaptors?

Thanks in confusion

Matty