32 bit, 4 way multiplexer
One way to achieve what you want is use dense tri-state buffers, such as:

http://www.ti.com/lit/ds/sces422/sces422.pdf

You will need one (2 to 4) decoder to decode address and drive enable controls for 4 32-bit buffers. Exactly one buffer will be enabled at any given time.

Here is one example image: