I have used both...they both work great guess depends on the look you want. One thing I found about mounting under the body on the frame is that you will need to pump more often even if power assit. the fluid rns back and even a residule(sp?) valve does not take away completely.
Here is a link to a few others we have done
http://smg.photobucket.com/albums/v281/iceburgh/franks%20truck/?start=all
http://smg.photobucket.com/albums/v281/iceburgh/truck/?start=all