I don't know about RPO codes but I will tell you this. On my Cameo there are two visual idicators that it is authentic. On the driver's side on the firewall "Cameo" is written in the metal. I guess they may have done this in the factory to signify it going to Auto-Fab Inc. This company actually did the conversion of the S10 to Cameo. It may not actually have an RPO code assoicated with it because it was not done by Chevy. I have some Cameo documentation that says:
"NOTE: Cameo and Camoe EL conversions performed by Auto-Fab, Inc. You must fill out and submit an Auto-Fab, Inc. order form"
Also this documenation details the *required* RPO equipment for Cameo. They are:
RPO D44 Black below eyeline mirrors
RPO N40 Power Steering
RPO QYH White-lettered all season radials
RPO ZJ7 Rally Wheels
RPO ZY1 Solid exterior color
Cameo EL only required:
RPO ZY1
RPO ZJ7 14x6" Ralley Wheels (vs. the 15"x7" wheels above)
RPO QMW 195/75R-14 tires (vs. the 215/65R-15 above)
Also on the driver's side door jam there is a offical Auto-Fab sticker that says it was modified by them and there is a date stamp on there of March 1990 I think. Mine is a '91 Cameo with Tahoe package. Here it is:
