1967 Barracuda Fastback Fold down door to trunk area?

The photos show it pretty well. It's a heavy piano hinge with stamped flanges, secured by bolts. The wood panel has steel threaded inserts to receive the bolts. One side of the hinge has a right angle bend to the flange, so it's not something you could substitute with a flat hinge. You might try Wildcat Auto Wrecking to find the hinge.