Unfortunately, from what I've gathered, dark brown interiors were only available for two years (I could be wrong...anyone?).No one seems to make reproductions in dark brown.Finding replacements can take time.Trust me, I know.My brown buckets weren't the best.A rip in the drivers side, cigarette burns, etc.
It took me ages to find a better set to replace them, and while ten times nicer, still have a couple small holes.
I'm keeping my old ripped ones to use if I need material for a tear or patch.
Try your local Pennysaver, Kijiji, etc.You may luck out.Forums such as this can be a goldmine.
Good luck.