Doug:
The front and rear I believe are different styles. The other problem is that the harnesses (pigtail wires on the sensors) are different lengths also.

Gilly

PS the sensors are made by Bosch, you may find a better price on them for the same exact part by trying to find a parts outlet that sells Bosch brand O2 sensors. You may even be able to buy them locally, although they may need to be ordered. may save quite a bit over MB prices.