70 Coupe diff. stamping

[Mike F.]

Stamping on the lower diff.. I know the CAO is for a 3:70, but what about the other numbers and letters?

Either
CAO 4 6 70 W or
CAO3 4 6 70 W

TIA,
Mike

[Randy C.]

Re: 70 Coupe diff. stamping

First, It's quite possible it says "CAO3 4 6 70 W". As you indicate, "CAO" means 3.70:1 . The "3" could very well indicte the shift that produced the unit. The "4 6 70" is the date produced - April 6, 1970. The "W" indicates the plant that produced the differential, which is Warren Motive. All of this came out of the 1970-72 Corvette Technical Information Manual & Judging Guide. If you don't have one, it's well worth the purchase. There's tons of info in this manual/guide that are most helpful in tracking down parts, date codes and so forth.

Randy C.

[Terry M.]

Re: 70 Coupe diff. stamping

Stamping on the lower diff.. I know the CAO is for a 3:70, but what about the other numbers and letters?

Either
CAO 4 6 70 W or
CAO3 4 6 70 W

TIA,
Mike

Randy has it. There is also a 1 in front of the CAO. It is quite common to see a number in front of the ratio code.

[John H.]

Re: 70 Coupe diff. stamping

The "W" indicates the plant that produced the differential, which is Warren Motive.

Randal -

Actually, the "W" is for the Chevrolet-Warren plant, in Warren, Michigan, which produced many of the Corvette suspension and driveline components.

[Mark S.]

Re: 70 Coupe diff. stamping

For 1970, what's the difference between the CAO, CAS, and CFA codes? All are listed as 3.70:1.

[Terry M.]

Re: 70 Coupe diff. stamping

For 1970, what's the difference between the CAO, CAS, and CFA codes? All are listed as 3.70:1.

It all depends on where you look for the list. Some lists are more inclusive of information that others. Some provide listmaker generated additions that are confusing, at best, and misleading at worst. It is best to go back to Chevrolet's documentation, but even that is not without confusion. The material in parenthesis below is my own words.

CAO is 3:70 ratio with Positraction (this is with the U-shaped axle attachments

CFA is 3:70 ratio with Positraction (this is with the bolts and solid caps axle attachment and is sometimes shown in lists as HD because that is the way Chevrolet lists it.)

CAS is also 3:70, (and is shown as without Positraction in Chevrolet's lists. Since Positraction is listed as standard on 1970 Corvettes we are left to wonder, along with you, what this one is.)