1969 Z 2/8 fuel line brace
 

What month did they put the fuel line brace that mounts to the carburetor and is there any markings on them.must be a rare part not much information on original ones how to tell from reproduction

Appears it started in production sometime during June, 1969.

Discussion here:

https://www.yenko.net/forum/showthre...l+line+bracket

Do you know if all of the were stamp with STAMP RITE early ones didn't

More here on CRG:
http://www.camaros.org/forum/index.php?topic=8747.0
As far as when, the 1969 AIM shows 10-31-68, but it was a running change and could take months to implement on the line (see bottom of this page):
http://www.camaros.org/AIM.shtml