All of the south african built 325i's had one from factory.
It is a metal plate the bolts to the front subframe at the rea, and has a tubular frame at the front that bolts to the chassis.
I can't find a picture on the web, but I could take one of the one on my car sometime during the weekend maybe? They are really well built.
Mine hits the road a fair bit (good for sparks at night???) and half the time I wonder if it wouldn't hit at all if I didn't have it lol! but the odd time I've tried going up a drive with a big lip in the gutter and its hit, and I've been able to keep going knowing I'm not doing any damage means I'll never remove it.
It's also really good to jack the car up from - just put the jack under the tubular frame and lift.