1970 Diff Code for L78?

[Mr70]

Both those 4:10's were posi.
I believe the reason for the two 1970 Camaro Posi codes,CRE & COO,was they anticipated the 1970 Camaro to recieve the LS6 engine from the line.
One 4:10 was to be destined for the L78,& the other the LS6.

This is true with the 1970 Chevelles.
The LS6 gets a CRW(Heavy Duty) 4:10 posi,& the L78 gets a CKK 4:10 posi if ordered.

Obviously the 70 LS6 Camaro never fruitioned,so they modified the two to be compatible with the L78 engine or LT-1 Camaro-Nova possibly?
Just a theory.