I assume the TC and the S2 are the same. My TC had a thick piece on the 'T', then a piece that wrapped the backbone, and lastly a very thick triangular piece that sat where the 'Y' of the frame.
I checked the S2 parts manual and it doesn't seem to list any at all between the frame and the body, but in section BF of the TC parts manual, the parts I just mentioned are 16, 11, and 18. Unfortunately, you don't get a really good idea of the shapes. 11 pretty much goes from the 'T' to the 'Y'. 18 covers the 'Y'.
I used 3/8" closed cell neoprene foam. 16 would be 3 thicknesses, 11 would be one, and 18 might be three (I still had that piece!). I got mine at a local rubber supplier, but if you can't find it locally, r.d. enterprises stocks it or similar.