axle codes

[tom anderson]

I have a 2004 F-350 powerstroke and am ready to change the oil in the axles. The axle code is D1. Does anyone know what this axle is? I plan on using Redline 75w140 in the rear axle and want to know if I still need to add the friction modifier?

[RRF985]

3.73 Limited-slip and I think with the Redline gear oil the friction modifier is already in it. I could be wrong though.

[late_99_PSD]

Your better off getting the oil w/o the modifier in it and then add the modifier in later. 9 times out of 10 they put too much modifier in it and then you LS won't grip.

[tom anderson]

Thanks for the info. I checked the Redline 75w140 oil and there is no modifier added in it. I added the 8oz of modifier as required in manual.

[late_99_PSD]

Uhhh, I guess I should have mentioned it before but the 8oz. is usually too much. The best way is too add 4 oz and go to a parking lot and do a few tight turns and see if it chatters. If it dosent then you good, but if it does then you need to add a little more.

But when I changed mine I just added 8oz. It does ok but I wish I wold have put less in it.