An attachment mechanism for effecting a load-bearing interconnection between a header and a feederhouse of a self-propelled harvester is provided. The mechanism has a hook element secured to one of the header and feederhouse, the hook element having a limb defining an edge of a jaw opening with a inwardly tapering edge for longitudinally aligning and receiving a transverse pin secured to the other of the header and feederhouse. The limb has a non-vertical face configured to engage the other of the header and feederhouse and align such in the transverse direction as the feederhouse is lifted to engage the pin and jaw opening.
