my mistake, but too similar in style to the triumph plate for my tastes for my super rocket.
the taylor dow simply appeared to be a slightly rotated triumph plate, but is slightly different
Yes, it can be confusing. The one in your photo is likely to be a Dow Duetto 5 or 8 since it's on a Triumph. The Duetto 2 was for 8"full width hubs as fitted to A7SS and A10 Super Rocket models. The 5 and 8 types were for various Triumphs and a 9 type for BSA 7" full width hubs fitted to A7,A50,B40,B31 from1958-63 and the Barracuda. They all had that peripheral flange and a horizontal TLS link adjuster.
Dow's Duetto 1 was for BSA's 8" single sided hubs fitted to the A10, Gold Star, RGS and 1965 A65.
Dow's Duetto 3 was for BSA's 190mm hub fitted to Gold Stars, RGS and Spitfires.
Both Duetto 1 and 3 did not have the peripheral flange but an angled TLS adjuster link and you can see Duetto 1 in my avatar photo.
Dow's Duetto 4 was for BSA's 203mm hub with 1 5/8" linings, fitted to the 1966/67 A65.
Dow's Duetto 6 was for Triumph's1966/7/8/9 full width hub with 1 5/8" linings.
Both Duetto 4 and 6 had the peripheral flange but with the angled TLS adjuster link.
Dow's Duetto 7 was for some Nortons, but I wont go there...
That's the total of my Dow Duetto info direct from his catalogue (not dated). I know this doesn't help Rocket Racer much but I enjoyed looking at the old Dow catalogue.