Dual Tanks on '74 Wagonmaster/Travelall

[MikeIIDC@domain.elided]

Help!!!

I finally have almost everything ironed out regarding this WagonMaster,
which is good, as I need to make some room and this seems to be the one
that I will let go.  I took it out for a test drive last Saturday night,
after working on it in the rain for some time, and it runs great... for
about 1/2 mile.  Then, the filters (I put one right after the tank and
one right after the fuel pump) get too filled with crud and it stalls
out.  I clean them, then it runs for a short while, then stalls, I check
them again-tons o' sand.  Clean them out, this time it won't start.
Filters remain dry.  I am assuming that there is so much gook in the
tank (passenger side, the switchover isn't working, so I have it hooked
up directly), that it is clogged up in there.  I added gas, so I know
that isn't it.
Anyway, getting the passenger one down is no problem, but in trying to
get it done right, I want to drop and clean the driver's sdie too.  How
is this done?  I looked under there, but ther is what appears to be a
solid box surrounding the tank.  It does not appear to be the tank
itself, as there are layers that the rust has eaten through, and there
is more solid wall in there.  This is in the rear driver's side corner.
There appear to be no bolts/nuts to drop this box.  It looks like it is
in a little frame that is mounted to the bed itself, or something.  Does
anyone know how to drop this?  I would really like to do it so that I
can have them both hooked up again when I get it done.  Any suggestions?

Thanks!

Michael