WA-8688 is GM's Brilliant Blue Metallic, a mid-saturation cool-leaning blue with a fine metallic flake, used across the third-generation F-body in the 1988–1992 production window. The color reads markedly different in shade than its blue siblings WA-8557 (Bright Blue Metallic — bluer, less violet) and WA-8961 (Medium Quasar Blue Metallic — darker, more storm-blue), all of which appear on third-gen F-body builds and are easy to confuse from a faded photograph.
On a Pontiac Trans Am GTA (Y84) the body-color treatment of the front and rear bumper covers makes the paint color particularly load-bearing visually — there is no contrasting black bumper to break up the silhouette, so the whole car reads as a single mass in whatever color was ordered. Brilliant Blue Metallic over the body-color GTA spec is one of the canonical period appearances of the package. ThirdGen.org's paint chart is the community reference for cross-checking surviving cars' WA codes against the original RPO callout on the SPID label.