I can see where there's some confusion on this one. I had a '78 Formula rear bumper soda blasted about a year back. It was all black but from an original 2-tone Formula. Once stripped you could see the outline etched into the bumper skin where the pin stripes had been between the two colours and also the Unleaded etc wording even though no decals were left during previous repaints. Whatever was in the decals seemed to have had a slight reaction over the years onto the surface of the bumper, you could feel it with your finger nail, the letters and where the stripes were, also discoloured like a stain even after paint removed.
And for what it's worth they also blasted a nose cone without removing the Formula decal first, resulted in raised lettering where paint/decal was blasted away at different rates but completely different to rear bumper and clear what had happened. It was not an original nose cone fron 2-tone vehicle so no lining or colour change lines to be seen.
Here's 2 pics, first one shows the fuel decal location but the photo doesn't clearly show the lettering up close. The second you can clearly see the different staining on the bumper side and where the pinstripe ran between black and gold paints. The lettering was more raised than the striping though.
