Thanks guys...
"Originally, the 1967 Camaro was labeled as a 5-passenger vehicle and 2 sets of front lap belts and 3 sets of rear seat lap belts were installed. Soon after the start of production, the rating was changed to a 4-passenger vehicle and only 2 sets of rear seat belts were installed for the remainder of the 1967 production."
The way I read this, if your tire pressure decal says 5 passenger than it would have gotten 5 seat belts from the factory... since mine only had 4 seat belts and is rated as 5 pass, the 5th center seat belt would have been removed by the dealer. My car bas built at the end of Dec 66 and sold in March of 67, since the letter would have come in February it would make sence the center seat belt would have been removed. Now I need to find another 52-A-66 belt.
Out of curriosity, approximately when did this change from 4 pass to 5 pass?