Fools alert!! O2 sensor Breaking news!!!!!!
 

The bosch O2 sensor and regina ntk are completely interchangeable despite the supposedly numerous technical incompatibilities!!!!!!!
Details coming later today....

not too many variations in how 02 sensors are designed. Mostly its whether your car has a heating element or not (ie 4 wire sensors have a heater and a sensor circuit). The big difference is the connector and cable length. That's why Bosch also sells a universal O2 sensor that you can splice into the wiring from the old unit. For example, you could also take a sensor meant for a Ford and splice it into your Volvo...

except a lot of newer engines use wideband ox sensors, while these older cars use narrowband.

I saw the reference to the Regina system so I assumed we were talking old, like the days when there were single wire O2 sensors :-)

regina was used on some 740/940's non-turbos

Never had an old NA redblock but I did own an 84 Audi which like the VWs of that vintage used K-Jet and had the early 02 sensor design. I had to drill that one out to replace after 250K miles