There is no "tried and true American" version. The US manufactures no airlifter between the C-130 and the C-17.
How many Puma IFVs 
can you fit in a C-17? Two. But that limits you in the number of airfields you can get the beast into.
Maybe you need a smaller prop powered airplane. How many can yo fit into a A-400M? One.
What about the "competition" How many can you fit into a C-130? Zero. It's too heavy, too wide, too tall.
The C-130 may have been Fat Albert 40 years ago, but today, it's not big enough. Of all freighters in development or production between 60 and 140 ton AUW, the Hecules is the skinniest.
Now they won't all find markets, but one or two of them will, and the marketing people at Lockmart don't seem to get that - the head honcho has suggested a widened C-130 may be possible in the late 20s. By that time the world's airforces will be flying European, Brazilian, Russian, or maybe Japanese.
What does reemplazos mean?