no power steering

hello

my father has a 1990
p-30 van(6.2 originally now is 6.5 deasel)
used to be a Keebler truck
it now hauls bread

any way
we put in a steering box (cause it was leeking)
3 years ago
had power steering then
then the hydro boost unit for the power brakes went out
and he says thats when the power steering went out
so we changed the hydro boost unit
bled the system(turned the wheels ect.)
and the power steering was still not working
so we thought the pump was bad
and changed it
then did the system bleed thing (turning the wheels hitting the brakes etc.)
and still no power steering
when we removed the resivoir
there were alot of metal shavings
on the maginet
just wondering where they may have come from
and why the power steering is not working
has plenty of fluid
not leeking
could it be the line going in to the steering gear box
maybe its plugged

thanks
for any help