Oil sending unit size (other than 1 1/16?)

[02Lightning]

The regular deep well socket I used would slide all the way down and touch the top of the valley tray. This is with the tray off the car, not sure if that helps you or not.

 

[exp500]

My guess is the socket you have is not fully broached, and you are running out of depth.

 

[chilleblanco36]

I know this is a couple of months old, but I just replaced my sensor today. I believe your socket is hitting on the shield sitting right in front of it. I had this same experience an hour ago. Also, I removed the OEM unit with a 12 point 1 1/16” deep socket. I had to use a 6 point to install the new one.