[pookie]

I can't attest to the measurement, but it is possible to do both sensors without dropping the engine. It's more of a pain in the butt, however it can be done. The short version

-Jack up the car
-remove driver side rear wheel
-crawl under and look on the driver side to locate the sensors and bracket
-there are (2) 5mm allen screws holding in both sensors
-if you can remove them without removing the bracket that would be best
(I wasn't so lucky and had to remove the bracket as my reference sensor was stuck in the socket)
-if you have to remove the bracket put the old sensor back in and tape a 8 mm washer on the end of it. Then bolt the bracket back in. The washer will make sure that the new sensor is at the correct spacing.
-Pull the old sensor back out and put the new ones back in.

Also if you do a search there is a thread with pictures showing you how to do it.

Good luck