Gas Tank Flush

[MikeIIDC@domain.elided]

Looking for some advice on what is the best way/product/chemical with
which to clean my tanks.  I have done this before, and kind of winged it
with water, broken glass, bolts, sand, kerosene and some Prestone
product.  Are these all of the ways there are, or is there anything
better?  The passenger side tank ('74 Wagonmaster) has a little "scale"
in it, but is not bad.  I don't have the cover off of the driver's side
one yet, so can't tell you, but it looks very protected and clean all
around compared to the other.
Also, should there be something rattling around in the tank?  The
passenger side one has something rattling around when I move it around.
Sounds like maybe a bolt, though I thought "golf ball" at first-does
that really work when you want to mess someone's gas system up?  Anyway,
cannot roll it into a location where I can see what it is, but it sounds
like it is on the anterior end of the tank-closest to the grille, I
guess.  I cannot think of what would be left loose in there, but, then
again, you all know how good I sometimes am at figuring things out!
I definitely don't want to clean it, put it back on, and find out that
my fuel delivery problem is still there.

Thanks for any ideas concerning any of this!

Michael