There are many different 4.3L engines and oil filters. Even remote vs on the block makes a difference.
Suggest you find your engine here,
https://www.mercruiserparts.com/v-6-sterndrive-engines and dig down to the block or remote oil filter schematics to find your correct part number.
You can cross reference to other filters once you know the right part number, but the OEM version is only in the $9 range.