Question for rear end experts

["Ed Esslinger" <edstiger@snowhill.com>]

 I'm Confused --  My work shop manual (WSM-145 page 23) indicates that the
standard 1725 Alpine has a 3.89 rear end, with overdrive it's 4.22.
   On page 15  Road speed /Engine speed there is an indication  that all
North American cars had 4.22 rear ends, when you compare the overdrive
speeds to standard. I hope this is true as I have installed an overdrive. Is
there any way to tell by serial numbers?--  Ed

Cool Cat Eddie ,1 S3 GT,3 S4's, 2 S5's, 2 MK1 Tigers
Deep South Rep TE/AE