Verifying 87 gnx parts

[William Novicki]

Trying to figure out if the gnx rims, fender flares and fenders w scoops on my car are authentic. Where are the numbers or codes or markings at n what should it say. Have invoices from Buick in 88 for my rims n caps n logos. Again need to verify this stuff is real

 

[X Ray]

Are the parts on a car ....if not the rims have two different offsets for the front and the rear it is stamped on the back of the rims. Fronts are -15 Rear are -23...the original center caps are all plastic no steel retainer in the back and of course the GNX sticker...the fender flares have part placement designated on the back side along with part numbers on them and are made of plastics not fiberglass...the vents are hard plastic not thin vacuform plastic material and also have part numbers stamped on the back side. Pictures would help to review...regards rick