1986-87 Turbo Buick 89 TTA Engine Oil Cooler Lines support clip.
So rare it isn't even in GM parts diagram! So yes this means no GM part number. If you have worked on these cars you know this clip gets hooked on to the oil cooler lines. It is generally mid-way in the center of the lines. The clip keeps them in tandem but far enough apart for low heat transfer.
Yes another part you didn't know you needed or were missing.