Good Luck with parts, six years ago I searched all over the world for one! I had the same one on our Perkins and one of the two cores failed, finally found a place that still made the cores at $2100.00 each $4200.00 for the two that are in the factory cooler. Finally replaced it with one of these from Seakamp in Seattle, here is an online page of it
NA001314CN Perkins Heat Exchanger at $325.00 Canadian, need a couple of 90 degree elbows to hook up the oil lines.
Just yesterday I installed another new one on the boat, as the original failure fill the Velvet Drive with seawater!!!!!!!!! Never again, now just replace it as regular maintenance ever 5-8 years.