There may certainly be differences between the year model Mopars. The early Barracudas do not have a differential switch (mine has no wire going to it). The distribution block is basically a hunk of brass. The comment that started this discussion was that a lineloc plumbed prior to the "Distribution Block" was not legal. That is just not true. The rule is explicit in that it talks about a "differential switch". If I remember correctly the 69 and later A bodies are a different story.

I have another 68 Cuda that is 100% stock, I haven't started restoring it yet. I'll check tomorrow to see about the block on it also.