I have a 56 Sunliner with 3 spd od tranny.  I think the car may originally had an automatic as the rear end has a 3.22 tag on it.  Specs for od are 3.89.  When I drive the car at 55 to 60 it does not feel or sound like it is reving at high numbers.  Is there any danger or problem with using the 3.22 rear end and how would one id the gear ratio is he pulled off the diff cover.  It is possible that there are even different gears then what the tag says,  a lot can happen in 60 years.