sure it is.
old john

yes it is
except that you might end up drying the fuel pump seals in the front tank if
you keep it dry, also watch you dont break the lines, they are a real b!tch
and you will prolly have to do them all the way to the front.

 i broke the plastic end piece off of my front tank, so i had to cut and
plug it because of the backpressure. then i forgot to put the backstop piece
on when i re installed it, so it was just transfering from one tank to the
other while it was running...to date, i still only a running on the rear
tank haha, so go figure, i turned a relatively simple project into a major
headache.

This thread, which I helped with years ago, my help.

http://groups.google.com/group/alt.trucks.ford/browse_frm/thread/d357168321ecf08
/a50f6a92d71cd858?q=dual+function+reservoir&rnum=1#a50f6a92d71cd858

If your fuel system is like mine then you need to know about the dual
function reservoir and  the fact that there are no less than three fuel
pumps.

Ford have a fix for the DFR when you go to one tank. Without it you
will have problems.