On Sat, 10 Oct 1998, David A. Cooley wrote: > I've found quite a bit of GM documentation that was erroneous. AC/Delco, > Bosch and Echlin all state the outer shell is vented which coincides with > my visual inspection of the sensor. > There are 2 basic types of O2 sensor, one vented, one not. Some Mfrs use both types.