FWIW, I checked out the Duebendorf Flight Museum web site, since they have a flyable Ju-52. One little gem I found is a .wav file of Ju-52 engine sounds.
http://www.airforcecenter.ch/fileadm...loads/ju52.wav
Assuming the engines are still BMW 132 radial engines, this would be a handy sound file for the Ju-52, as well as the Ar-196, FW-200, and Hs-123.