I went through this exercise a couple of months ago. I have a 3/4 drive SAE socket set and the closest size is 1-7/8 which is a bit over 46 mm. It works fine to remove the fuel sender but not so well on the fuel strainer, which is difficult to access with the big and heavy socket. Driving it was very difficult if not impossible with 3/4 drive. Reducing down to 1/2 or 3/8 was also very difficult because the drive shaft was in the way. . The nut on the strainer is very thin (a little over 1/8 thick) and the chamfer in the socket does not help and it keeps slipping off the strainer. I think I did try to grind the chamfer away but it didn't help (still slipped off). Maybe if I started with a 46 mm socket it would have worked OK. I ended up taking the tank out. The ideal tool is not a big heavy socket but a 46 mm thin box end wrench with a bend in it like the valve adjusting wrench. One of the wrench in the Harbor Freight fan clutch wrench set may possibly be modified with a bend (if the 40 mm is a long handle and can be ground out to 46 mm).
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=90341
After I got the strainer out, I cut the strainer off completly . I didn't have the parts at the time but if I get my hands on another strainer I will cut the strainer off and add a floating pickup and never worry about bottom gunk or water.