'73 Dash Harness Question
 

what year dash harnesses are a DIRECT interchange for a '73?

I'm guessing '73 and '74 will work, but any other years? I know the '70 and '71 are different where it mounts to the firewall, as well as the plug-in on the back of the gauge cluster.

Held for Ransom, you out there? :)

From what I remember, 70 - 74 are physically the same where they go through the firewall. 75 and up are bigger to accommodate more circuits. As far as a direct replacement, I don't think there is one other than the 73. In 74, they added some stuff for the seat sensors in the seat belt circuit, and it has that extra relay on the inner fender under the hood. I think 70 and 71 are the same wiring, but 72, 73, and 74 each have there own unique wiring.

Once you get back to 72 and back, the connector on the gauge housing is different ( but you can re-pin the correct connector with the wires and a diagram) I would stick with 73 or 4 and thats it.

Fairly certain that there's no DIRECT interchange, James. Pontiac engineers putzed around with stuff like that every model year . . .

I found that the size of the harmonica connector for the gauge cluster changed around October/November '71 to the larger one. As said above, the position or the wires in the connector, as well as the number of wires/connections changed often so you would want to make sure the printed circuit you use on the gauge cluster matches the harness you use.

Yup. All are different.

thanks for all the input, guys.

So even though a '74 might be slightly different, will it fit and work on a '73 (everything plug in)? What about a '72 harness?

72 will not be plug and play, on a 73 it may work, but I suspect differences where the connectors for the seat belt buzzer connector are,and a few others under dash.
72 harness on a 73 is easiest, have done it 2 times now, but it wasnt just plug and play for everything, that is for sure.