The Rover-Landers of BC

I'm changing the fuel guage(or sender?) unit in the fuel tank. I have two issues.
First, the one I've pulled out has two wires, one being a ground, the other going to the gauge in the dash. The one I want to fit is new, has prongs for three wires, one being a ground, the second prong has the letter W next to it and the third prong has the letter T next to. Is anyone familiar with this?
The second issue worries me alot more. My old unit is sealed. I see no wires in the parts that are in the tank. The new one I want to fit has two wires with exposed connections (the two wires W & T) in the parts that are in the fuel tank. It just seems wrong... and scary.

What vehicle??? If Defender, one is for a low fuel light. Some trucks do not use it (some don't have lights, some use the sender signal for the light). Not sure which is which, but an ohmeter will tell you.

W = warning light
T = transmitter

Two of my Land rovers have 2 wires joined in the fuel tank. They are very solid connections and no probems. In my case they are for the fuel pump.
Cheers
ted

Ok I've got the terminals.T and W. The truck is a 1970 11a. I've only got one wire going to the tank. I might wire in a warning light .
What about the exposed wires though? I see the rheostat(?) plain as day as well as the wires(unsealed exposed). All this will be exposed to splashing gas as well as vapours. I just want some more opinions here before I fit this thing in. I'd hate to do it wrong and then they make a movie about me!!

All the Defender ones I've seen are like that, fully exposed wires and resistors.