I have a t3 (it is currently being utilized), but I know at least the thigh braces are the same as whats in the project (or at least they fit) and would assume other boats. I can't recall how the hip pads attach, but I think they are just wrap arounds and as far as backband you should be able to substitute for it fairly easy and I would think the drain plug is fairly universal too. The seat may be a bit harder to come by.
It may be worth posting on Wave Sports forum and asking if they have anything. They seem to check it frequently enough and someone may be able to help you find what you are looking for.
"I plan to leisurely advance through my existence" - Terry Fuhrman 1991