This was being discussed back in 98 and 99. I posted the following over on the NCRS board back in Aug 99:
Check the new issue of Vette Vues (Sept 99), it has a write up on the "black box". Basicly it is the air bag controler that has had some "extra" features added. It is located in the center console below the radio. It maintains in memory the last five seconds of data and then at the moment of air bag activation (and in some case, near activation) freezes that info into memory. Basicly, besides air bag deployment info, it stores the vehicle speed, engine speed, throttle position, and if the brakes had been applied.
For 99, besides the Vette, it is installed in the Firebird/Camaro, Cadallac Eldorado, DeVille, Seville; Buick Century, Park Avenue, and Regal. The article goes on to state that the C5 Service Manual has 75 pages on the subject.
tom...