I was looking at my Haynes manual for 1980-1996 Ford Pickups and wanted to know what rear axles we have.

What weight should I use for the front and rear?
Are they both the same weight.

Ford rear axles (conventional & limited slip)
Hypoid gear lube (Ford part no. XY-90-QL)

Dana rear axles (conventional & limited slip) Hypoid gear lube
(Ford part no. C6AZ-19580-E)

Thanks for any help as this is a Great site.

 

Your truck is gonna have the Vistion(sp) better known as the Sterling 10.25, or the 10.50 for a dually. The Dana 80's came in the F-Superduty (F450) trucks.

Either way, for the lube, I highly recommend a quality synthetic. Either Amsoil, or Royal Purple. You will the the 75w-140 weight. You shouldn't need a friction modifier if you have the limited slip. However, I found my LS to chatter a little around sharp turns. So I add about 3oz of friction modifier. I believe you will need like 2 1/2 quarts of lube. But I can't remember for sure. So just get 3.

And as a disclaimer, DO NOT get the friction modifier on you!!!!!!! It will stink for 3 days and no less. Trust me. LOL

 

So our trucks have a LS rear end. I didn't know that but just in case adding the friction modifier wouldn't hurt.
Thank you Rubberduck for your help!

 

Not all of them. Just look on the tag on the rear diff cover. If it says 4L10 it's limited slip. If there is no L it's not. I think it also says on the door tag, but I can't be for sure.

 

Just looked at it and the tag says 4L10 so that's cool. Thanks again RubberDuck.

 

Do you recommend or use the 75W 140 due to the mods on your truck or is that the weight our trucks are better suited for.

Most vehicles do not need a 75w140 gear oil. Unless it is specifically recommended, a better choice is typically a 75w90 or 80w90 gear oil. AMSOIL has a Series 2000 75w90 gear oil based upon the same technology as the 75w140 that is an excellent choice for all but the most demanding conditions. Even big rigs use our Series 2000 75w90 gear oil with excellent results. Moreover, fuel economy is far better with a 75w90 than with a 75w140.

 

I used Red Line 80W140 High Performance Gear Oil (synthetic) when I changed my transfer case and rear end gear oil about 25K ago. It was recommended by a FTE member at the time, but I don't think he posts in this 94-97 forum.

 

I thought the transfer case runs ATF like the 5speed.

73, I run it because I'm pretty sure that Ford recommends that weight. Would you be okay with the 90, I believe so. LOL

 

your right, they only use ATF, mine, i'm running transynd(no mercon rating) but never gear oil in the transfercase, at least I'm not that brave.

 

75W 140 sounds good to me and yes we do use ATF in both our T-cases and trans.
Next time I change my fluids I'll look into the Amsoil for the trans n t-case

Thanks for all your help!!!!!!!!!!!

 

the 5 speed doesnt run standard atf, the stuff it calls for is very pricy, i cant recall the part number but its synthetic mercon.

and i use ford synthetic 75w 140 in my rear because i switched to the superduty 10.5 carrier and thats what it calls for

 

I think the pricey part is the word synthetic. Can be found at any parts store.

Synthetic Mercon is correct.