Ford 9” Help

[SBR_GUY]

I have a 67 F100 4x2 Styleside That i am restoring.
I have had the rear end all rebuilt. The tag reads WDM-H NL anyway. What oil does it require, and do I need a friction modifier.

Also T-18 trans. What oil does it require and any additives?

[cep62]

I would use 80 / 90 wt gear lube in the diff & trans.
If you think you have a limited slip diff you can add a friction modifier , it won't hurt if you have a standard open diff.
a way to tell if you have a open rear is to turn one wheel , if the other side turns the other way you don't have a limited slip.

[SBR_GUY]

Thank you for the reply. Much appreciated.