I bought some lit at a swap recently, in it was a Olds Radio listening pleasure brochure. It shows an 8 track, so it's late 70's I would say. (78-81)I usually find Pontiac ones, I never saw an Olds PC, anyway, I deal in Pontiac stuff, so anyone needs one post it, I'll send it to you. Goes in your glove box stuff.
Slight water stain but it's old, lol.

 

Here's a pic