What other radiators are compatible?

Because that is a rebadged Ford Explorer but a limited run version due to the changes in 1999 you are somewhat limited in parts. The Explorer unit from 1996-1999 and the Mercury from 1997-1999 are the only direct fir parts. Now if you wanted more cooling and can do some fabrication work you could opt to have a custom one built but those are generally much more money than the available parts.