The GM locking gas cap I ordered came in the other day. It even has a groove for the cas cap tether! In order to remove the tether from the non-locking cap and install on the locker, I used a hair dryer to heat up it up around the cap. This way it can be pulled off without breaking it. Then ya have to heat it up again and real quick pop it into the groove, and work it around until it pops on. Pretty slick!
The part number is GM 10326376, group 3.028.
The part number is GM 10326376, group 3.028.