Wrong discs for 304 cab?

[misterbridger]

Bought a pair of replacement front discs for my '74 304 cab a while back off ebay, and the central raised part is shallower by a good quarter of an inch. Are they wrong, and if so can someone point me in the direction of the right ones, please?. Failing that, does anyone have any experience of in situ disc grinding?

[Dave45]

It's the diameter of the disc that is the difference. Yours should be 256.5mm. Models from 1977 onwards had a diameter of 263mm. That's according to the Haynes manual.

The early type are hard to come by and when you find them, they're expensive.