Thanks for that. I think i'll just try making up something from a block of foam. I would like it if i could find the proper surround for the core, but for a car thats 27 years old, i'm lucky to find anything good to use!
If worst case I cant make up something i might just have to use a sealer like selly's.
Thanks for your suggestions....
EA Fairmont Ghia : 3.9L MPFI, 2.5" cat back sports exhaust, K&N panel filter. Pioneer head unit, pioneer 4" three way fronts, Pioneer 6" 3 way rears, 2x 12" subs, blue interior light.
My main pride and joy : '76 XB Fairmont GS, 250CI, 140,000 Km and all stock.... for now! (Factory air-con on the way)