The suspension depends on what you plan on doing with the truck. If you plan on taking it off-road like I do, Its best to invest in a new suspension. Those off a full size truck are a different size, they won't fit without doing a little bit of custom fabrication. That and they are meant to have more weight applied to them since the F-series is a heavier truck. But one thing is for sure, what type of tranny do you have in it? The T5 from a mustang will fit perfectly. If you rebuild the one you have with stronger gears and such, and change the bell housing, it would work. And your rear end, it may not be strong enough for the torque being applied, since it is set for a much smaller engine. I ran into those problems when I swapped the factory 2.3 turbo in my old mustang for a 302.
For your ordering, I recommend <a href="http://www.summitracing.com/">Summit Racing</a> or <a href="http://www.jegs.com/">Jeggs</a>. But there are many others out there too. just Google it