10" high performance clutch?

must be a 9.5 then, i know it didn't get the right one at first when i replaced it. All the sites list my car as having a 10.5" and the 6 cyls having a 10" which i figured they used the same clutch for my cuda. I have the 273 commando in my 65 cuda with the 833, i love it but with simple upgrades it wont hold the power and i got a ton of chatter(prolly a bad stocker). I plan to put a 100hp shot of nitrous on it and i know even a good stocker wont hold that much.