If you know ahead of time your going to make a tube chassis, skip buying the whole clod and just buy the axles, unless you want to run the stock wheels and tires.

Even if you cant afford a bruiser Tamiya is released a High Lift(similar to a Bruiser) with a Toyota Hilux body, and has already released one with an F350 body. They are not cheap but they are also not nearly as pricey as the vintage trucks are.