68 GTS Trunk Trim Panel
They are around $500 for a new one, and a long wait also. My friend just received his new one for his 69 GTS, nice piece. He had to wait about 4-5 months to get it. Classic Industries has them for 68's also. It may be worth just buying a repo one than trying to find a nice original. Maybe you can fix the pitting in yours using solder or something similar?