1970 Chevelle rearand questions

[69L72RS]

I need re-educated a bit before I look at some parts this weekend.
For some reason my mind stops at 1969.

I am going to look thru some 12-bolt rears/parts that an old man has listed in the local trader. All of the parts are supposed to be from 1970 Chevelles.

He has two 4.10 rears, with different codes, that he says are all original from cars he wrecked.
One is CKK 0627B and the other is CRW 0221B.

I bought two KK 0627B rears that were from 69 L78 Chevelles last year.

Would the CKK 0627B rear be a restamp, or would the "C" have been added if it was installed in an early 1970 Chevelle.

My book shows the CRW rear is the HD 4.10 (LS6 only).
Is this rear setup the same as the "KQ" rears were?

I don't want to pay good money for something that has been tampered with or has the wrong parts in it.

Thanks in advance for your help.
Eric

PS: Let me know if you want me to look for anything for you.
It sounds like he has leftovers from several cars he has wrecked.