Like my W124, mine did not come with a front plate bracket (some states didn't require front plates). So I glued 2 small locknuts on the inside of the rubber bumper insert and then re-mounted the insert back onto the front bumper. I then used short bolts and tightened them to the locknuts to fasten the plate (and plate frame). This has held so far, considering that I performed this job in 1998!

__________________
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car