[dagnabbitt]

I have two 67 GMCs, both have SPIDs. They are Oshawa trucks.

I suspect that some factories were either slow to move to SPIDs or put them on the inner fender where they would get destroyed or replaced with new inners.

You might get lucky and find one under the seat, I would check. I have never been that lucky, but I hear about guys finding them there all the time.