If you want an old truck, don't let these guys scare you off. True there is more maintenance work with an older vehicle, like point adjustment every 1000 miles or so, brake adjustment and the like. But most of the expendable parts you need are available at your local auto parts store. And there are truck parts suppliers that have nearly every part on the old trucks.
I have a '54 GMC Suburban that I have put over 18,000 miles on in the last 2 years. It has a stock 248 six with an SM319 overdrive. I can drive 75 on the highway and get 16-17 mpg. I installed power front discs for slowing it down from 75. Putting around on the back roads I've gotten as much as 21 mpg. I have eliminated the point adjustments by using a Pertronix ignition.
I'd recommend an Advance Design ('47-55) or Task Force ('55-59) series or their GMC counter parts, the New Design and Blue Chip series. Any of the stock sixes in them are economical and dependable. Outfit it with an overdrive transmission and go for it.
If you get a '47-54 you will need to change to open driveline for an overdrive. The '55-59 have open driveline.
