Smoke - I don't know why it's different, but my 03 owners manual says 75W-140 for the rear of 1500's. That is the same as the online owners manual I downloaded from Dodge for the 04. Both say the additive is necessary. Wonder if they changed the lube specs or maybe we have different differentials? What are they measuring when they talk about the 9 1/4" and the 11 1/2" diffs? Inquiring minds want to know.

 

Ring gear size. 11.5 comes in CTD trucks.