Thread Size

Hey all,
just wondering if anyone knows what size thread is on the front loop of a Triumph frame (1960 duplex) that you bolt the hard tail section too. The lower bolts - one is a straight through nut and bolt type set up and one lines up with a thread into the front loop, that's the one I'm after

This is the only photo I have, it doesn't help too much, the bottom, back 2 holes where the hard tail tab lines up, the one that the most rear.

Cheers

pulled mine out of my 500 frame and its 7/16th 20



kinda hard to see the match up on that tho (the thread count that is)

Awesome, thanks heaps for that.

no worries