I had real trouble finding a suitable alternative oxygen/lambda probe for my 1992 Rev 2 MR2 Turbo. I can’t find the original Denso part number at the moment, but I managed to find that a Denso DOX-0107 fits the flange size correctly and is 1-wire, it just requires soldering to the original connector. It’s got a Flange 44 type flange which apparently matches the 3SGTE.
For my Stellaris Launchpad engine simulator, I wished to add a calculation of the Air to Fuel Ratio (AFR) or lambda/equivalence ratio for the current engine conditions. I did this crudely by using the throttle position, engine speed (this->s) and current fuel pulse width (this->F) as factors in calculating the AFR: