I believe the raised splashwell tub (like the one pictured below) that you're looking for fits only the early Moesly/Potter 20' CC/Seafari/Sceptre models with the seats at the transom. Instead of seats, the MA and later CC models made by Tracker have full height storage boxes/bait wells at the transom and just a transom gate between them, so it's a totally different setup, much like that on the 18.
Here is the
thread about the mold that Don Herman made from one back in 2012.