Hmm- thought I could give you an easy answer, but there is a lot of discrepancy in the information.
- the manual states that there are 8 identical steel plates and one with a larger internal diameter. This is what I found when replacing my clutch. It is one of the 8 larger plates that has the groove.
- your schematic shows three different plates (all #9, but with different part numbers). One plate of one, six of another, and one more of the third. That's eight plates not nine. Also, none of those part numbers match the triumph numbers I found. That doesn't look like the 3R/GT. Looking up one of the part numbers I believe it's for the Thunderbird.
I bought the kit T1171015
Although you can't order individual plates from that site, it does show the two different steel plate sizes and as you can see this is a different bike than the one you are viewing. Their schematic looks different...
Here's the manual.....
So, just be careful getting the right plate. Based on my experience and the information in the manual, there are two different sized steel plates. Eight of the larger size (smaller internal diameter) and one of the smaller size- same outer diameter, but larger inside diameter (bigger hole in middle). On my bike one of the eight larger steel plates had the groove. Unfortunately, I can't recommend the correct part number since I got the kit. I'm not sure you can get the individual parts for our bikes, but maybe a dealer can get them for you.