Found a bit more 9511 info on this below CRG link w/ more clarification Copo 9511 was req'd to get 4:56 / 4:88 only and 4:10 available w/ RPO G84...
http://www.camaros.org/pdf/options.pdf
Note beside RPO G84;
4:10 available as the RPO alone..
4:56 and 4:88 req'd Copo 9511..
Also note under the 'requires' column is 12x37 for Coupe only
(so there goes the ragtop Copo possibilities!)..
Nothing indicating it required any specific engine so a Copo 9511 6-cylinder car possible?.
Also waaay down the page 9511 clearly notes 4:56 and 4:88 ('69 only)..
Keep digging!.
[img]<<GRAEMLIN_URL>>/beers.gif[/img]
~ Pete