Firewall wire loom holders

[Chevystep]

Does anyone know of a source for these firewall/inner fender/hood "push in" wire loom holders? Some of my originals are toast and I'd like to replace them. I guess failing finding them I could use black zip ties and round off the locking portion to push it through the holes, just figured I'd hit the forum and see if anyone has found them. This one broke, but the wire loom goes through the loop, gets tape wrapped in place and the round knob holds it by pushing it through holes in the firewall (or inner fender, hood or back of the instrument panel).