Because the gears are referring to reductions, higher numerically is
lower gearing. Volvo had 2 different final drives, (they called them
1030 and 1031) they used different gear sets. In the "old" days, the
1030 was for the 4 cylinders, 1031 for the sixes. This maybe the
difference in "offset of hemisphere" as mentioned by athol. The 1031
type was in the higher ratios (lower numerically), and was in Volvo's
words "somewhat stronger". However, by the end there was some crossover
in the middle ratios, 3.91 and 3.73 were both available for both types,
and maybe some others too.
Also, as mentioned, installing a ring and pinion is a job that requires
precision measuring tools, shims etc. to get the clearances and contact
areas set perfectly, or the gears will howl or even grind themselves to
pieces.
--
Mike F.
Thornhill (near Toronto), Ont.
NOTE: new address!!
Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)
