3/8-24 locking nuts wanted

Hi folks.
I'm in need of some 3/8-24 self-locking rod cap nuts. They have small slits on the top allowing for deformation. They are NOT castellated nuts.

These are for a '54 331 Hemi.

Tried numerous car parts stores and local fastener outlets to no avail.

Tried APEX, ARPS, McMaster-Carr, Graingers, and others too.

Attached Images
File Type: jpg 3_8-24 Locking Rod Cap Nut_1.jpg (20.2 KB)
Author: gatz