$250 for that is an ABSOLUTE smoking deal - the caliber of a deal that I'd wager only a select few of us might get -
Congrats!
I have understood that the Camaro could have a four leaf spring, which determined different perches vs the Firebird which always used three leaf springs (and the shorter perches) - I do not know if the differential housing code changed with the different perches.
This rear was the "performance" ratio offered for the '70 Trans Am and Formula 400;
For the Firebird line this ratio was only available with a posi;
For the Trans Am a posi was standard;
For the Formula posi was a required option with this gear set;
For the both models this gear set could be ordered with the automatic (M40), wide ratio four speed (M20), close ratio (M21; was a required option; M22 not offered).
I hope some of this yammering helps someone.