So on my quest to improve my mpg (currently getting 9-12 mpg) picked up some new O2 sensors. Denso 234-4756 and Denso 234-4744. My plan was to only replace the upstream sensors the originals are still in the truck at 105k never thrown any codes just a shot in the dark for improving my mpg. My issue is I took the advice from a reviewer on amazon who said "234-4756 is for upstream right (pass) and downstream left (driver). Part number 234-4744 is for downstream right (pass) and upstream left (driver)." I know rockauto says otherwise but rockauto also says 4744 will work on the downstream right does this mean downstream left is the same? The only difference I see between the two is the length of wire.
4756 on rockauto says it's for the downstream left