1970 LS6 block and 1971 LS6 replacement block
 

Factory CRV coded 1970 block casting number 3963512 dated J-24-9 and is 60 over. I stand behind this block as original and not restamped $5,000 with standard 7416 crankshaft, 7/16 factory dimple rods, timing cover, harmonic balancer and oil pan. 1970-1971 factory CE1 service replacement block casting number 3963512 dated F-25-70 with front pad of CE152671 30 over with one sleeve $3500. Both blocks were magged at the machine shop. 330-770-2517