by dave-r » 05 Apr 2008 12:02
You can't. The blocks are the same. There is nothing on the block to tell them apart. At least in 1970-71.
Not 100% sure about the '69 1/2 R.Runner/Coronet engines. They were different animals.
Many 4bbl engines from 1970 even have the same crank, rods and balancer as the 70-71 six pack cars.