That part number was only used on ST185 & SW20 3S-GTE engines.
I wonder if an oil cooler assembly (bracket and the cooler) from an ST205 would be an option? The o-rings on the block side are identical. Can't just get the bracket, as it is different and requires the cooler also. Might be worth checking into, unless someone has a blown 3S-GTE they are otherwise going to scrap and can pull the bracket you are looking for off and give/sell to you.