1970-1970 brakes interchangeable??

[northerncuda2021]

Good morning all. I'm in the process of ordering new disc brake setup for my Cuda. I got a set of spindles off a 1974 challenger, my question is when I look to order parts on Rock Auto its telling my the rotors are different from 70/71 to 72/74. Also the 70/71 rotors are sold out but 72/74 has lots of avaliable .   I cant physically see any difference ?? Is there any difference???  Correctness is not important to me as long as it doesn't effect safety.
Thanks

[Bullitt-]

You need the '74 rotors & bearings as they will fit the '74 spindle. '70 was different in this area, otherwise they readily interchange from what I understand

[MoparLeo]

The difference is the spindle diameter. 70-71 use a smaller inner bearing so the later 70-71 rotor will not fit the later 
/larger diameter spindles. Just order 73-74 parts. No worries.

[anlauto]

The newer ones 72-74 have larger bearings...and different seals...if you have 1974 spindles, be sure to order everything for a 1974

[northerncuda2021]

Thank you guys. Even better the 74 rotors are cheaper.
Take care