I started a thread on Tanknet with my analysis of the MBT-70 protection; you can see it
HERE
Very Early Calculations (may be disproved by Tanknetters)
This calculated gives us the following statistics:
Frontal Hull Protection: 253mm KE, 312mm HEAT
Side Hull Protection: 100mm KE/HEAT
Gun Mantlet Protection: 449mm KE/HEAT
Side Turret Protection: 194mm KE, 227mm HEAT
Rear Turret Protection: 63.36mm KE/HEAT