Horn Mounting - 18S

[LoneStar]

OK, this is a pretty basic question but I can't find a useful picture to assist. The horn is said to mount on my 1954 18S with these parts:

- 014195 L-shaped bracket attaching to engine plate
- 015245 L-shaped bracket with arms to attach to the horn
- 015705 nut, sleeve, for horn fixing bolt
- 000402 horn fixing bolt, 3/4 x 3/8 x 26
- a flat washer and a lock washer for the bolt
- 015706 2 rubber washers
- 015707 plain washer for the rubber washers (?)

I have these parts, except for the 015706 & 015707 which I was hoping to improvise. But I'm not clear on how they all fit together. The sleeve nut takes a 3/8" bolt thread, but its shank is c. 9/16" and won't fit through any of the bracket holes or the engine plate hole (they're all 3/8").

Here's a pic: http://www.vincent-hrd.co.uk/images/horn_mount.jpg

I'd guess that one of the holes involved has to be drilled out to 9/16", to accept the shank of the sleeve nut, and the 3 washers ride on that shank. Where should the sleeve nut be? Where are the washers positioned, and what does 015707 do for us?

Thanks,

Dave