NC8 - Chambered Exhaust

[Mr70]

I have a Chevrolet Technical Service Bulletin #69-T-8 issued Dec.1968.
It states that on November 25 1968 the NC8 Chambered Exhaust system was no longer Standard equipment on Camaro SS & Z-28 and Chevelle SS,but was now optional,due to the excessive noise levels deemed by some local police depts.
It goes on to say the RPO NC8 will still be available as optional equipmentin those areas where the system is permissible.
So I believe this to mean it was possible to get it optionally,depending on where in the country you lived.
But when I open up my 1970 Assembly Manual,it says that RPO#NC8 is cancelled for good for the Chevelle as of May 19, 1969.
This adds confusion as to why the 2 later Chevelles stated early recieved it so late in production.