Thanks for the response guys, does anyone have a picture of this 3/8 port on the lower intake ? What tools will I need to open that port properly, as I don't want to mess my intake up.
In the past Mustang5L5 has posted pics of the port. It's just an easy-to-spot square headed plug.
To remove it without removing the plenum, you need a 1/2" drive socket (the actual size of the socket doesn't matter - just the fact that it's 1/2" drive), some extensions and tape.
Put the socket on an extension, but put the socket on the extension upside down (so the square drive is facing away from the extension, The extension will go through the body of the socket). Use tape so the extension only extends into the square receptacle about 1/2 way (insert it half way and tape it so the extension can't slide into the square receptacle further). Now you can put the extension and socket onto the plug. The socket, which is upside down (with the square part facing downward) fits the head on the plug. Use a ratchet wrench to break the plug loose (some PB might be needed since galvanic corrosion occurs).
Then install the factory sender in this port and extend the sending unit wire (or pull it out of the factory harness) and attach the wire to the factory sender.
I suppose one should be prepared to pull the upper (just in case). A plenum gasket is requisite for that (they're a few bucks at better parts stores).
Dress the threads on the sender to help seal them and ease removal in the future.
FWIW, aftermarket senders are about 5 bucks at CSK (or so they were last time I checked).
Good luck.