Re: Cut off date for Chambered Exhaust
 

The memo states that NC8 was cancelled in all cars in production effective May 19th 1969. That means any car that didn't have the exhaust already attached to it at 8am on May 19th would get an RPO N10 dual exhaust system.

COPOs might be an exception but I would imagine that GM removed all the parts to make up a chambered exhaust from the assembly plants on 5/19 as well.