Fuel economy?

[sven557]

I might be getting a 66 c10 longbed, it has a straight six, and I believe it has a 4 speed manual. I don't know too many specifics right now but everything on the truck is stock. This truck is in pretty good shape. Right now it belongs to my grandfather and he's kept it shedded for at least the past thirty years. It runs fine, gas tank has a small hole somewhere near the top, brakes leak, and minor rust; but nothing that is too hard to fix. I'm not planning a total restoration, just fix it up to good running condition and continue to use it as a work truck on the weekends.
I know these old trucks use a lot of gas but I want to know a general baseline for what to expect. How many mpg is normal for this truck?

I've been looking around the forums for a couple weeks now and see alot about swapping out drum brakes for disc brakes. What is the advantage of disc brakes and is it really worth the effort?

Thanks