Hot Rods Mallory Magspark Distributor Application Information Needed

I recently purchased a Mallory Magspark ZCM distributor that is a model 301A

Now I'm trying to find out with a 100% certainty what it's application is.

Here's a couple of photos of the unit in question.

Wish I had an old Mallory catalog

Thanks in advance for any and all help.

Tom

 

looks like 54 mercury, ie. Y block

 

Thanks Jim, That was exactly what I needed to see.