[Hotrodshop]

to have on a Jan. build date 1970 SS. A two piece front rotor on one side and a grooved rotor on the other side from the factory? Even the disc brake shields look a little different. As far as dirt, rust and under coat overspray they look the same age.

 

[Mike]

Have the casting dates for them?

 

[LS6 Johnny]

Remember, your Chevelle is 40+ years old. Break calibers fail all the time taking out the rotors. So they may have been replaced only after a year or two of service.
Your best bet is that it was replaced at some point in time.
To be sure, check the part#s and casting dates, and compair them to the build date of the car.

 

[67shovel]

X2 on what John said

 

[Hotrodshop]

After further checking the rotor was replaced in 1974. Thanks Guys