[Frank v R]

some of the holes are for your C42 set items, you should also have the holes for your signal lights , these were not the same as the CDN 2 & 3 , the housing is the same but the lens used was a blackout marker door with the cats eye removed with only the clear lens remaining , using a normal clear bulb not coloured , the signal area should have a total of 4 holes , two for the housing , one for the bolt , one for the locating pin and two more for a aluminum bracket that was to keep the housing from movement ,this applies to the fender only left or right , for vehicles with the C42 set on the pass side the marker is mounted to the plate that is bolted to the fender for mounting your ATU, the aluminum was over kill and I do not know if all the signal kits were installed using this part , on the rear you should find 2 or 3 more holes at the rear for mounting two L brackets for the rear lights , lights used were of a commercial type with red lens on one side only , when I restored my wifes '53 I did not install these because it looks like something a farmer installed ,but I did leave the holes, the '52s , '53s , and all the smp vehicles had these kits installed during the same time period , you can still find the rear lights on most of the GMCs, hope all this helps,
regards Frank