I have .. but mine is a 1989 90 ... with a '97 Disco front and rear axle!
Mods needed were the front brake lines are on different sides, so bracket fettling needed, quite easy. I reckon you could use the Defender calipers with the brackets already sorted, I didn't even try it as the parts were a tad corroded ..
For interest, as mine had drums on the rear axle, when I put the rear Disco axle on I also had to fettle a rear plate to hold the slightly different brake line configurations, I dunno how this would be for the newer Defender, but it isn't hard anyway!.