Salisbury Diff Identification

Can anyone tell me where I could find an identification chart for pre 70’s Salisbury diffs, or any proper information, please? What diff was used in what car originally? I have a 2HA diff ( stamped 2HAO,on the inside, ratio 49/13) which is mounted in a 1957 MK I, but does not appear to be its original diff. On the outside/underside it is stamped D57 468, which someone told me means it was produced in the fourths months ( A=1, B=2, C=3, D=4 ) of 1957. Can somebody confirm this?
Cheers Gerhard

I think if you will re post this on the E Type or XK120-150 forum you will get answers. A photo of the markings will help identify what you have. Nick

Thank you, Nick. I’ll try this. Cheers Gerhard