joew,
If you need a new sender I have a new sender in the box for $45.00 and I will pay the shipping to a US address. I bought it but never needed it and never installed it - it is still new in the box. These sell for about $56.00 I believe. The open ended wrench which fits it is around 14 or 17 MM. I have a stubby one in my tool box and will get it out tomorrow and see the exact size. The problem with putting a wrench on the sender is that the space between the back of the sender and the engine block is very narrow. I got around this by putting the wrench on my bench grinder and "thinning" it up a bit.
You can get the wrench on the sender by removing the radiator overflow tank and coming in from the right while kissing the top of the intake plenum. Once you get the wrench on the back side of the sender, angle it toward the rear of the engind and use a hammer handle to drive it down and off. It is a great temptation to screw the sender off by twisting the body of the sender. Don't do this until it is quite loose on it's threads. It is easy to twist the outside casing of the sender in relation to the base, and if you do this you will break the wire inside which goes to the spade connector your gauge wire hooks up to. On reinstallation of the replacement sender, the final tightening can be done by leavering on the wrench with a tool against the firewall.
Look for a new post from me in the morning and I wil give you the exact size of the wrench and maybe a photo of the ground down wrench.
Robert Hill in Memphis, TN
[email protected]