For example if you have a lock core with 061 then you can use the replacement key for thule and sportrack racks and carriers part thkeyn061.
How to open thule roof box without key.
Take great care to go in straight and not drill the plastic edges of the cargo box.
This will depress the spring mechanism and the tab.
Pull the lock barrel out of the cargo box.
Push down and in on this tab with your small screwdriver.
If you have lost the change key enter d1251 in the search box below to order a replacement.
Enter the part number below to search for keys and locks.
Disengage the lock mechanisms once you have drilled all the way to the opposite side of the barrel.
You can see should you get the box open the aluminum rods bowing in toward the inside of the box as the box has gotten shorter as the temp has gone down.
When you open the box during warm weather the rods are flat against the side of the box.
We surfed a bit on the internet and lastly found an excellent and elegant solution.
This should pop the lock cylinder loose.
Enter the exact code found on your lock cylinder otherwise your lock might not be found.
Pull the lock barrel out of the cargo box.
Position the drill bit into the dead centre of the metal barrel.
Disengage the lock mechanisms once you have drilled all the way to the opposite side of the barrel.
Important to install or remove thule lock cylinders you will need a change key.
The other option you have would be to have a locksmith drill out the lock core you have now and then replace it with the replacement lock core and key for sportrack part sr03807 which is not a direct fit but should still work for you.