Hi i blew the gears in the diff and i was thinking what ratio gears i should put it its a mk2 escort panelvan

kind of an open ended question and very much a matter of opinion.
did you like the ratio that was there? if so, then replace with the same.
if you were revving the engine too much, throw a longer one in (3.54:1 from a 2L sedan)
if you wanted faster acceleration then try find a shorter one like a 4.1:1 

I have a Mk2 panel van 1600 daily driver until two years ago.
All mechanically factory standard used in metro traffic.
After experimenting with ratio swaps I found by far the best option for driveability and fuel economy was the 3:54 ratio.