I had the starter off of my 66 GT350 on the weekend for it to be fixed and was surprised with the casting date code of my block. (block is the original Ford VIN stamped)
I had written down the casting date as 5H10 with an assembly date code of 5J3 for the block and the heads both with a casting date of 5H20.
But the block is casted 5G10 (not 5H10). Assembly date code is definatley 5J3. So the block sat around for a couple of months before being assembled - is that unusual? Heads are definatley 5H20 - double checked.
REgards
Rohan