[V8Vairs] 4.56:1 Corvair Diff?

[paulsiano@aol.com]

I bought my 1966 Corsa tubro new and four years later started a Crown conversion.  I have always been under the impression the differential was 3.55.
 
...and then this email arrived today from Don Sherman:
 
 
 
I also met with your engine builder and his lovely mother.  This
prompted a few calculations which I just made.  I am convinced the
final drive ratio in your car is 4.56:1.  That matches perfectly to
the observed speeds in gears--39 in first, 55 in second, 82 in third
and 120 in fourth, all at 7500 rpm.  Do you find that credible?
Surprising?  sincerely, ds
 
 
 
Do 4.56 ring and pinions exist for Corvairs?
 
I'm all ears.
 
Paul