Chevy continually revised Camaro ordering information, options and prices. The April 1, 1969 listing has this notation:
Axle, Positration Rear G80: Ratios 3.73 or 4.10...also includes HD radiator.....$56.90.
The manner in which it is listed is confusing as it includes 'Special Performance Equipment' and mentions '396 engine' without mentioning L34, L35, L78.
The Canadian Price Schedule is more succinct:
Axle, Positration Rear with 3.73 or 4.10 less C60 (includes V01).
So at some point after April 1 ordering a 396 with 3.73 or 4.10 positration axle (posi required with those ratios) included HD cooling at extra cost. Must have even confused Chevy as some later COPOs list G80 @ $56.90 on documents, some do not list G80 at all.