On my '01, I used a 32mm to remove the factory sensor. I think that may be the same as 1 1/4"... . it was just what I had on hand since all my real tools were at work. I used a 1 1/16" to install the new sensor. Both were standard 6 point deep sockets. My sensor was on the driver's side of the block, just above and forward of the starter. Oil did not come rushing out when I pulled the old sensor.