3.42 vs. 3.73 gears.......

Since your thinking about a 5th wheel go with the 1 ton, and if the 5th wheel will be over 13k gross, buy a dually. You'll never regret it.

I have heard some say "buy your second RV first". When we bought our first 5ver (used)I knew that in a few years we would want a bigger RV. I went straight to a F350 CC, PSD dually, and the only regret was not getting a 4X4, not so much for the RV but for snow and mud. because it is my daily driver.

Depends a lot on what truck you are looking for.

Most have double overdrives, and effectively will run the diesel engine at a lower RPM than in years past, no matter what rear axle ratio you are using.

So are you looking for a 2500, 3500, single rear wheel, or dually? Or F-250 or F-350?

If you plan on graduating to a fifth wheel in the 30' length, with a 12,000 GVWR, consider it should have 20% of that weight on the hitch pin. So that would be around 2,000 pounds.

If you also have a crewcab, and plan on taking along 500 - 800 pounds of passengers, generator, some firewood, ect. then this can add up to another 200 - 500 pounds. This might require a F-350 with a 3,800 - 4,000 pound cargo rating to tow such a large fifth wheel, though a 2500 or F-250 with a cargo rating around 3,000 pounds is fine for just about any travel trailer, as even the largest are only about 11,000 GVWR, with a 1,200 - 1,400 pound hitch weight, and are not a problem for any of the modern 2500 trucks.

Best thing to pick up now is a towing guide from each of the three big truck manufactures. They discuss GVWR in length, and you can pick up a lot of information from the brochures.

It also has the GCVWR of each truck, with various rear axle ratios.

Fred.