As far as I know it's smaller than the standard Mondeo one as my mate was only on about his the other day so you'd probably need a blank to fill the hole left.
As a side note, his is the ghia so may have a bigger stereo than the LX so not 100%
Definately fits, my original stereo now resides in a 51 plate Mondeo Zetec.
It was from the 2003.75MY (6/03 build) that the Mondeo gained a larger stereo. Prior to that all Mondeo from 97-03 used the same large bezel stereo as the Puma.
Ah..that's why I thought it wasn't right as my mate's is a 54 reg. Sure he said his was 1.5 din whereas the Puma is 1.25 din.....or something like that.
Anyway, who care's....it will fit so everyone is happy.....lol