Later Tonneau fixation for XK 120

Working on the Tonneau for my 1954 XK 120 OTS. This is the final version with “Lift the Dot” fasteners at the front and “Durable Dots” at the rear sides of the Tonneau…
The studs for the Lift the Dot fixation at the front are listed as BD.1749, having (according various sources) a 2BA threaded section that would fit in the tapped holes of the side pillars.

The holes in my side pillars, however, are much smaller than 2BA. These holes have a thread with an outer diameter close to 5/32". This might refer to either 3BA or BSW 5/32.

I noticed that Lift the Dot studs are available in No 8 -32 UNC, as this size is apparently the “military” version used for the restoration of all kind of equipment. I don’t think that Jaguar would have used No 8 UNC versions in the Fifties but BSW 5/32 comes very close. But 3BA would be more likely I assume.

Does anyone recognize my problem with a threaded hole at the lower end of the side pillars in which 2BA doesn’t fit?

PS: I have meanwhile fitted these No 8 -32 UNC studs (according the supplier) and they fit perfectly. But they might well be 3BA as these threads are so close. Both a No 8 nut and a 3BA nut fit on these studs (as used for the front centre fixation of the Tonneau near the rear view mirror).

Bob K.