Just googled... a 20 inch mazda oil cooler, about the same size as a setrab 172... is $100 new!!!
ALUMINUM Oil cooler MAZDA RX2 RX3 RX4 RX5 RX7 S1 S2 oilcooler
Is this the type you were using? I may end up going this route. Cheap enough that its worth trying. The Setrab is $600+ or so...
As the mazda is aluminum, welding on AN fittings should be pretty easy...
Anyone used this model before?