Slant 6 Manifold Nuts

Hi there,

I'm looking for the special locking nuts that go on the slant 6 manifold. They fit into a slightly tapered brass bushing and look almost like a castle nut (highlighted red) See photo below:
1388571-5fde14d58a58e11477437eacc0214d0f.jpg
From the photo it looks like there are two versions of the brass bushing that the nut threads onto, the ones I have have the small lead in I'm assuming this is the right nut for them. The other style of special locking nut to the left in the photo would probably work as well.
Thank you for your time.

Slant 6 nuts.jpg