Hi grs600, with diesel they will run for ever. If you services them regular.
Look out for...Timing belt, when it was changed.
when it was serviced.
if it is a turbo, make should there is no turbo lag. ie( lack of power).
and just general if the body as been looked after.
I have a peugeot 306 lx diesel, and that as( 167,345) miles on the clock. i service it regular, and i have not problems with it.