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.

Been a long time, let's see if I get it right. I'm assuming an open rear end-no posi.

Properly jack up and block the car, rear wheels off the ground. Put a chalk mark on the driveshaft. Have a buddy hold one wheel and turn the other one 1 turn.Count the revolutions of the drive shaft. It'll get you close.

A 3.2 something with the O/D is only going to be good downhill at highway speeds. I've been there and done that. How's the car start in first on a hill?

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ

Miker,  isn't that two revolutions because of the open diff?  An alternative to having a buddy hold the opposite wheel is to just jack up one side.  If you can get both sides to turn together one revolution would be good.

Don

If the axle ratio really is 3.22 the effective ratio in OD would be 2.25 I don't see how that can possibly work so I suspect a previous owner swapped in a numerically higher ratio. Most OD equipped cars had final drives ranging from 3.89 to 4.11.

dbird, I stand corrected. Like I said. It's been a long time. I'd probably have figured that out when the ratio came out at 1.75.

Dobie, your right. My 312 with the T-85 O/D and the 3.something Dana wouldn't make it at under 70 on flat highway in O/D. I swapped in a 4:27:1 out of a 6 cyl O/D wagon, still a Dana in those days. But that was back in the 60's, when the junk yards were full of them. That's why I asked how it started on a hill. Mine wouldn't.

miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ