I want to put the equivalent of one of those truck - Delta Pro
Aluminum Single Lid Crossover Toolbox things in the back area of my
2006 4runner. I have not worked out the dimensions and measurements of
alternate boxes, but there is a good chance that it will fit. The
standard truck tool boxes, while strong, are a half a foot too wide
for my rear storage area. Perhaps there are some other boxes, even for
purposes other than this, which might serve.

I simply must have some relatively secure portion of my 4runner, as I
must carry around papers and valuables and the like. Only when stopped
in questionable locations would it be of concern, but it is of
concern.
I could use ready to buy Master Lock type steel cabling that could be
put through eye hooks bolted into the box and then the cabling would
run under the seats to anything that would accept having it wrap
around. It would not stop someone with a blow torch, but would cause
some definite time delays.

Then, if a great need arose to take it out of the back, so that
something else could go in temporarily, I can do that.

Needless to say, this is a first series of thoughts. Any suggestions
from out there ?