If you are buying the complete assembly, bracket and filter, it doesn't matter. The reason it says Mercury is because Mercruiser and OMC used different thread sizes on their stern drives. Recommend spending a little more money and get a Stainless Steel bracket and a Racor filter.
Get the best for your gasoline engine, a long lasting stainless steel bracket and a Racor S3213 filter. 10 micron aqua bloc media with blue see-thru bowl. 60 GPH. Requires two hose barbs that can be ordered below. Replacement filters available below.