[FFR428]

The C8 tag is the original Ford service part number. The D3 tag denotes it's a 73 service block. The 6010 is the number for a bare block only. 6015 is a production block used in a car,truck etc... You are right that many service blocks have no casting numbers. As long as you can id the block in person to verify it's a NOS sideoiler you should be fine. I'm sure the block is a pretty penny. Some service castings have been known to have some issues so you might want to have a competent shop check it out. There might be a reason the block is still NOS. But it also could be fine you just never know and better to be safe.


G.