Without comparing side by side would think that the 68 version would be much longer in length since they must travel and attach towards the front of the hood and the 69 at the rear.
Jeff:
The 67/68 headlight harnesses have a two pin plug just forward of the firewall grommet for the hood turn signals. It appears this was a standard feature.
The 69 headlight harness does not have this two pin plug, but I do remember there is a separate sub-harness that plugs into the turn signal 3 pin plugs and feeds a two pin plug that ends up near the firewall. The original poster is wondering whether the harness that plugs into that two pin plug is the same for 68 and 69.