833 dust cover I.D. help

[72dustervs]

I have a bell housing 3515734 10-1/2" clutch A-833 1972-1973 A-body B-body E-body 318 340 Aluminum and bought a dust cover sold as an sb 10.5 cover but it does not appear to line up to bolt on , does anyone know what this dust cover fits ? The number stamped on it is 480E373

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