Another difference noted: 73 to 74 cars (dash cluster)

[Craig74tii]

In your first picture posted, below the round multi pin connection, there's a purple stamp that looks like 119. If you look on the same place on Keith's cluster you'll see a male connection.

That connection wasn't on the '76 4-speed I parted out.

IIRC it did have the 3 pronged connection that you mention, and it was covered by a black rubber cover, so it wasn't used.

[jgerock]

You're absolutely right Craig. The spacing between the lamps is different. Wonder if that tab is for a ground wire?