clutch question for Apache

[chevyfiftynine]

Hi truck forum,

I have a 58 Chevy Apache half ton stepside 235 6 cyl 3 spd and the clutch is worn out and needs replaced. When I measured the old clutch it doesn't match the sizes available. My clutch disc is 9.7/8 diam and the bearing 2" at the small end. Cover has multi fingers and is 10.1/8 diam.

The size Classic Parts of America have listed is 10.1/2 disc diam. How can the size be different? Is it possible the wrong clutch has been fitted in the past? There's no other clutch before or after '58 that matches mine. I can't order a new one till I work out how come this clutch was fitted to my truck.

Any ideas?

Regards,

Barry.