12 Bolt with 4.88's

Just found out that the 12 bolt i bought that was out of a chevelle has 4.88's. Would this have been a factory option?

 

Depends on the year....check it out here.

http://www.thecamaro.com/Decoding/Chevy-Axle-Rear-End-Decoding/Chevelle-Rear-Axle-Codes.php

 

According to my books, the highest numerical ratio available from the factory in a Chevelle was a 4.10. That's not to say that it couldn't have been dealer installed but chances are if you pull the cover and look at the ring gear you won't find a GM stamp on it.

 

1966 Chevelle 4.88 Posi. KO
1967 Chevelle 4.88 Posi. KO
1968 Chevelle 4.88 Posi. KO
1969 Chevelle 4.88 Posi. KO

KO being the axle code.

 

Believe the Baldwin Motion Cars were available with 4.88 gears.
Bruce in Alaska

 

Splitting hairs probably, but KO (4.88) and KM (4.56) were dealer installed. I guess I misunderstood because the original poster asked if it was factory installed.

 

Some how I have to disagree on Factory installed ratio 4.56 I have a KM coded rear and I DOUBT tghe dealership stamoed that code in the aXLE TUBE. Just another thought.

 

I agree, that part had me scratching my head, too. Still, I've got several Chevy and Chevelle books and not one of them states that either the 4.56 or 4.88 were available from the factory, only dealer installed o No:

 

thought the 454 (ls6) 4 spd (m22) ss 1970 chevelle could be ordered with a 4.56 gear.