Volvo J type OD ratio %

[Don Malling <dmallin@attglobal.net>]

I have a Volvo J type OD with the following markings:

On passenger's side: LM22 115240   13 SO (maybe SG?) 7427
On driver's side: DTS 117930 LA4

I understand the gear ratio % can be determined from the numbers on the 
OD case. Can anyone tell me where to look to determine the gear ratio % 
or do you know what it is? I understand it can be something like 25%, 
27%, or 28% ?

Thanks,

Don Malling