I have a '47 1 1/2 ton, all original.

What is everyone using for gear oil for their transmission and rear axle? I am not draining, just topping off, so I want to try to use whatever was most likely used before.

Owners manual says to use S.A.E. 140 (for summer) gear oil for transmission, and a mild gear oil (again S.A.E. 140 for summer).

Thanks

 

I put 85-90 in both the trans and rearend, unk said when new it probably had 140.

 

85-90 is quite universal. Some use 75-140 as well but from the information I've got, 85-90 should work if you plan to merely top up. If you plan to change the oils, then you might want to consider flushing everything out and using a synthetic oil. Some use Amsoil or equivalent and it does calm down the whine of your crash box somewhat.

 

Thanks guys!

One more question. Where is the fill plug for the transmission? Left/right, high/low?? My transmission is completely covered in dirt and grease.

 

on my 42 4 speed its on driver side. used an ajustable wrench squire plug.

 

You need to post some pics... Is your avatar your actual truck? If it is, it looks NICE!

 

My avatar is the truck indeed!