Distributor Hold Down

[Towd56]

I have what I believe to be a Mallory electronic distributor. Im looking for the hold down device that clamps around dist. Shaft and then sits in the head with a pin. Anyone know where I can get the right one?.

I'm afraid if I just use the set screw - the dist. Will walk on me- throwing it out. As you can see my head is aluminum so I don't want to put a lot of torque on that set screw.

Thanks