I have a 2014 Chevy Express 2500 with the composite headlights so I will use that as a guide.
Ready to attempt this upgrade on my 2017 Chevy Express 2500. I already have the new grille and headlights.
**** I am looking for the part number for the harness so I do not have to cut the wiring. Does anyone have this ??

Parts List for 2017 Express 2500 Grille & Headlight Conversion
22816425 - New Grille with Chrome - includes new center emblem
15879433 - Composite Headlight Assembly Left - OEM includes Bulbs
15879432 - Composite Headlight Assembly Right - OEM includes Bulbs
11609385 - Grille Nut Left/Right - Need total four for both headlights
11589039 - Headlamp Assembly Bolt Left/Right - Need total four for both headlights
12101898 - Connector Right/Left for High Beam - must solder or crimp - need 2 - or need part for harness
12101897 - Connector Right/Left for Low Beam - must solder or crimp - need 2 - or need part for harness


Radiator Support for Square Headlights
Radiator Support for Square Headlights
Radiator Support for Composite Headlights
Headlamp Assembly Bolt - GM (11589039) Need 2 for each side Total 4 - 2 for each headlight + 2 retainers (Nuts) also required
11609385 - Grille Nut - Headlight Retainer - Need Qty 4
Genuine GM 12101897 Headlamp Low Beam Connector - Need Two
Genuine GM 12101898 Headlamp High Beam Connector - Need Two
Square openings above square headlight need Grille Nut and Headlamp bolt - pic from my 2017 Express 2500
See 11609385 - Grille Nut and Headlamp rusted Assembly Bolt - GM (11589039) - pic from my 2014 Express 2500

 

how hard it is to change the radiator support to install one for the plastic lights??

 

You really don't have to replace the radiator support, you just need to cut a little bit of it away with something like a dremel, or even a rotozip if you have one. Beyond that, probably not too hard to replace if you go that route (replacing), but there will be some cables, wires, hoses, etc. that will need to be removed then reinstalled after you put the new one in.

If you have a newer van, you are probably on your own. Mine is an '06 and I didn't need to replace the support