Differential ratio - 99 Bluebird/ International

[frank-id]

Take the bus Vin number to a local International truck dealer. For a modest fee, the dealer will provide a build sheet for the bus. Frank

[crazycal]

The plate on my 89 BB has the ratio on it.

[martian]

If you can get to the bus, take a brush, rag and some carb cleaner.
Dive under the rear and find the axle data plate. There are probably at least two.
One describes the axle, the other has the ratio on it.
First one was on the front of the tube, right side.
The one displaying the ratio was on the pumpkin, front right side.
On mine, anyhow.
If you can't find it, use the VIN, or it may have the build sheet in the nose.
Not sure if this has the ratio, but should have all info on how it was spec'd.
Lastly, you can drive it and figure from there. Governed at 2600 rpm, with
approx. 40" tires, lockup in top gear (if it has a lockup torque converter).
Calculate the ratio. Rocky-Road.com has a very handy gear calculator.