Just picked up one of Gibson's unusual guitars, an All American II (1996). The guitar is two single-coils with a Strat-style vibrato, but mine was missing the whammy. It's a 3/16" bar with a 10/32 thread (as best I can tell), and inside the cavity, unlike a Strat-style inertial bar, the threaded post hole is straight through (second photo, lower left) - so forget about dropping in a tension spring, it just falls out.
Can anyone tell me more how this is supposed to work? Thanks ..