here is a great site for info on the powerstrokes, especially the 7.3...
charles ledger the ford master mechanic who owns this site,
also answers questions on a yahoo user group for the powerstrokes...
PowerStroke : '99+6.0/6.4/7.3 Diesel S-Duty,Van &Excsn
his answers are brief, to the point and amazingly correct.
he's covered the antifreeze/scoring issue on the above site (first link) and many other important issues on the powerstrokes.
he keeps a complete list of the tsb and service issues and other goodies up there.
i've learned lots from his stuff and he's correctly diagnosed my rig multiple times, online and for free.
check it out!