On summit they show some Earls coolers at first look they look like they have the AN fitting made in them.
But in the notes it says -10AN O ring fitting size and fittings not in included.
You could go from -12AN to -10 O ring fitting to plum it.
Earl'* Performance Temp-A-Cure Fluid Coolers 82500ERL - Free Shipping on Orders Over $99 at Summit Racing
Now I know your thinking don't down size it for flow but I drought it really would make much difference.
It actual might give the oil a chance to cool more to fast a flow can not give it enough time to cool off.
The old saying no thermostat can make water flow to fast and not have time to cool off in the radiator.
On alibaba they show a lot of coolers to I found
Heavy Duty Truck Oil Cooler, Heavy Duty Truck Oil Cooler Suppliers and Manufacturers at Alibaba.com