You are a bit limited in choices since those seats are fairly narrow. The outer sides come very close to the helm walls.
Your seats may be Todd.
This seat is close.
An excellent choice to upgrade existing seats in many cases. The marine-grade vinyl covered foam cushions are thick, comfortable and removable.
www.toddusa.com
The outer dimensions are the critical specs.
The seats don't generally include the mounts. There are lots of options, the two key measurements are the pedestal diameter (2 7/8 for yours I suspect) and the seat mounting bolt spacing. You can reuse your old mounts but by now, things like the slide guides are probably worn out.