I do not think you can use the blade disc off a power torque on that.
Thats the oval disc. It hits on the bolts that attach the handle to the base. Might be OK on yours as they look to be nut up.
Theres two disc diameters. A smaller round one that takes long utiltiy blades. And a 2 different large round ones and the oval one that use the shorter utility blades.
So the one in the store thats smaller, if its listed as utility only, with the long blades it will be right.
Your disc could be the larger one. (was fitted to rear catcher full crank and early power torques) and it works on a utility with the shorter blades. These blades are a lot easier to get. Bunning have them on the shelf. (bloody expensive, less blade and near twice the price of the normal blades)
The other style large ones were crack prone. Ive had to throw everyone ive found in the bin.
I should have asked this first, whats wrong with the disc??? Looks OK in the picutre.