from "Aeroquip" a few years ago just in case I needed it !!..........<:) It is bound to work on a 13B if it helps your 20B
Kelly;
Be aware that these units are limited by the water-side heat transfer. MoCal sells a flow restrictor (about $5) which forces more flow through the annular passages that are in close contact with the boundary between oil and coolant. Since I’m only putting about half the coolant flow through that cooler I put in the restrictor which significantly improves the performance. If your planning on full flow, you would want to check the pressure drop curves before putting in a restrictor.
I estimate that in my installation the oil/water cooler is handling about a third (or less) of the total oil heat load.
FWIW,
Al