The ring at the end of the spring can go onto an installed J-hook (Banjo Brothers sells the type pictured above). It can also be hooked onto the spur at the bottom of the rack strut, where present (looks like your rack has them). You have two positions on the pannier for the bottom of the spring. See which one fits on the rack best.

Those panniers are dead ringers for Cannondale Overland panniers. They're likely made by Cannondale for Nashbar.

[MENTION=305894]oddjob2[/MENTION] If the plastic sleeve with the internal spring is too long for your rack/frame set-up (which it looks as if it could be from the top picture), there are two things you can possibly do to remedy this:

First, head to your nearest ACE or other hardware store with the current spring and sleeve in hand (they detach easily at the top screw) and they should have a similar spring in different lengths. Purchase a shorter one and using a hack saw, shorten the plastic tube to match. Most likely you will need to position the bottom slide bracket further up on the pannier as well.

Second, move the current spring higher on the back on the pannier. This will require removing the screw, creating a new hole on the internal plastic frame, and moving the bottom slide bracket further up on the pannier as well.

Time to customize these old panniers to keep them working!

Yes the C-dale racks were really tall so PastorBobs suggested mods are probably the way to go.