I have a 1977 ford f-350.there is no tag on the rear end.what gear oil do I use?

Ford PN-C6AZ 19850 E, SAE 90 Hypoid Gear Lubricant is what was in it new, any lubricant meeting Ford spec ESW-M21C105-A will work. If your truck has a limited slip axle you will need to add friction modifier to it also.I have a 1977 ford f-350.there is no tag on the rear end.what gear oil do I use?
75/140 is what I would use.I have a 1977 ford f-350.there is no tag on the rear end.what gear oil do I use?
80w90 is what you want to use
SAE 80W-85W-90W gear oil
85/90 will do it.
90 WEIGHT
80w90 or straight 90w
we use to call it 90 wt, but now there are multis, like 85-115 and even synthetics, you can even add friction modifiers if it's a posi
90 W