Mazda Forum - Mazda Enthusiast Forums - Need Some Help with a 99 S model

Hi all Mazda Milleina owners I have a 1999 Mazda Millenia S That the engine light keeps coming on I took it up to autozone and they read code P0134 Bank 3 or 4 can't remember. So I believe it to be an Oxygen sensor. My Mechanic put it on his machine and pull the same codeand another code a P1554 which he didn know what that one meant. Buthe did say the Last oxygen sensor behind the catalitic converter was the culpit ithad a reading of .74 and didn't move. This thing burns gas like you wouldn't believe So my question is does anyone know what the be replacement oxygen sensor is to get? An where is Bank 3 and 4

Also I have been trying to find Left and right Front struts for this thing and I have only found one place online that has them Autopartsworld.com for 192.00 For one. Does anyone know and good place to get these? As you know all the parts for this car are expensive

Thanks