plastic trim pieces

The pieces I'm looking for are for another project car... a 77 Buick Lasabre, looking for the inside B pillar interior trim. This trim is so brittle that even touching it, it crumbles. Thought if anyone knew of a place that could make them I'd be back in business. These two interior pieces & the outer rear bumper fillers is all I need & car will be complete & done almost as good as new. Thanks for your reply, Ralph