Just go to Rockauto and look it up. Econnomy version is Stock application. Centric makes a replacement for 70, $55 ea. Guy on the Ebody forum bought them and was really pleased for his Challenger. Rotors use same part#. Don't forget 5% discount if you order from them.
Centric rotors at $50-$60 ea for the 70-72 application are just rotors, you'll need to disassemble the hub from your old rotors and install it on the new rotor, complete assys with a new hub from Centric are $140-$150 ea
Another consideration for the OP is using the unicast 73 and up rotors available at any parts store, DrDiff has bearing sleeves to fit the rotors so that the smaller inner (70-72) bearing can be used with the 73-up 1 pc rotor, I've done this conversion many times, zero issues