If I leave my truck parked for a day or two, I will find 2-3 nickel to quarter sized splots of oil under the truck where the drive shaft meets the rear axle. Is this good/bad/normal? Do I just have to feed her a little lube? If so, what kind and how? I believe it's a dual speed rear end, but never operated it (does anyone know how?)

 

Sounds like you've got a failing/failed pinion seal. And while it's not ideal, it's a pretty big job to replace simply for a tiny oil splot or two. It's probably a good idea to check your oil level, but it could drip like that for years without ever becoming "low". On my priority of list of things to do, that's a project that would be right at the bottom. My 2c.

 

I had the same problem on my 9 3/8 and ended up tightneing up the cover plate bolts, then running a tube up from the breather, then finding it was getting oil that was dripping and flying back from a loose oil line up in front of the engine. I took care of all of those and come to find out I had a leaking brake line fitting that was dripping down it.

Pinion seal is a good possibility too. I'd clean and dry it off really good then go for a drive and see where it leaks from.

 

How does one do that? (The only experience I have with rear end maintenance is I watched my uncle replace his pinion gear on a much much newer non-ford truck)

 

I think you just fill them to the top.