Hmmm fitting the lights would be easy, Just drilling some holes into a Mk2 Jetta slam pannel to mount them, It would be constructing a surround and grill that would be the hard part. I guess you could use an existing Mk2 grill and place that between the lamps, Mounted on the slam pannel, But you would have huge gaps between all the pannels and the lights that would need to be filled by some sorta custom fabricated pannel to plug the gaps?

Could prove pricy. however if you look at the Mk3s front end, The lights look almost identical to the jetta lamps on the outside, on the inside towards the grill they vairy in shape. You could get away with the tops of the lamps by hiding them using a Jetta grill spoiler and you could probally cut the two small parts off the Mk3 lower grill spoiler to fit under the lights, Then make them join to a Mk2 grill and you would have the grill 99% done, All you would need to do after that would be to cut some metal to wrap around the inside parts of the lights and to match up with the Mk3 grill. Using the existing grill from a Mk3 wouldnt work because of the size difference.

