Welcome to Just Commodores, a site specifically designed for all people who share the same passion as yourself.
Ok, does your wrench engage the inner tabs or the outer ones?.. I use a universal (its adjustable size wise) fuel tank locking wrench, TOLEDO brand
available at decent auto tool stores ( I bought mine years ago, worth its weight in gold, especially
with early Commodores which use an oring. The tool rotates the locking ring without twisting the oring)