I bought my 68 last fall. I finally am confident about the number on the axle tube. It was hard to get to (above RH spring perch) and I couldn't make out all of the numbers. The number is QK0614G2. This is a 12 bolt, but it is mounted on mono suspension. Is this right or could it be a 12 bolt from a 67.

Thanks for the help

The key is to look at the casting code/date on the center section. As far as QK the only year my reference material shows it available is in '67.

Only seen QK as a 67 axle. Doubtful it's original. Does it have a radius rod bracket on it?
What's your build date?