Distributor cap

I have a 327f Chris Craft engine with a IBM 4115 distributor what is thecorrect part number for a new crab cap Sierra?

Related question does anyone know what this cap fits?

The correct distributor cap is an AL – 145 which is no longer available. It is the flat cap that looks like the Mallory but is completely different. We do have some new old stock distributor caps for them if you would like to call and discuss it please feel free to 201-445-8685. As far as I know, there is no Sierra replacement.

Found this on CCABC Boat Buzz

. from searching–need distributor caps for my 1965 Connie–283F engines w/IBM-4115 Prestolite distributors–Sierra no. is 18-5391–everybody’s …

Don’t know the sierra number but it has been obsolete for years. IBM 1049