MIHELA
1-5-6-3-4-2-7-8
It's the same axle. If you replace the vent fitting, you can run 75w90 without worry and in cold places like here in South Dakota, you WILL notice.
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The TSB mentions that 9.25 diffs and extreme cold with 80W90 can cause failure due to lack of lubrication. 2004+ vehicles all came with the white vent and 75W90 from the factory.