I got a 1978 Dodge D-150 Macho PowerWagon and i'm curious about what kind of oil weight i should use. Also i'm planning on changing the tranny fluid along with the differential fluids so i'm mostly curious as to what lube as to 80-90 or should i use something else. And the same thing goes with the transfer case. Anyways if you can let me know or help me out that would be much appreciated.

 

im assuming 4speed since your suggesting thicker oils. if so put lucas 75w-90 full synthetic in the trans and rear end. wont have to change it for a long time that way.
I'm not sure on what t-cases use though. someone else will chime in on that.