We have a few parts for a brand called "InAqua" ( used a modified Fleck Valve Design called the 9400, also sold under "Wolverine" brand ),
see: Main Piston = 9000 Top Piston
**
Also,
see:
Valve Replacement Guide

and
Recommended replacement ( if your current valve is the InAgua or Model 9400 ),

Fleck 5600 Econominder


The Tank is standard opening ( standard 2 1/2" x 8 NPT opening looks like 2 3/4" ).