I'm running a Casper's heated O2 setup. Can't remember exactly how long I've had it in the car, but I've probably run about 25 gallons of leaded thru it over the past 2 years and it's still working fine.
2 years isn't bad. you can get replacement sensors for i think 59.00 which is about what the denso's go for. how are they as far as switching and warm up? alot faster than the single wires?
The denso 4 wire Heated O2 that replaces the one that will plug right in to Casper's heated O2 kit is the 234-4018 with the SQUARE 4 pin weatherpak connector.