Hi, I have a 58 beetle that I want to install a vdo sender and gauge. The sender is the style that fixes to the neck of the tank with one bolt. My question is, can someone please post a wiring diagram. Any help would be much appreciated.

Without knowing what type of gauge it is is hard but most of the early units had a power wire to the gauge and the other terminal went to the sender unit,this earth through the body of the sender to an earth wire connected to one of the tank mounting bolts. Try the operation prior to putting it in the tank as sparks are the last thing you need near fuel.
NOTE-general description only and no responsibility accepted due to too many unknown factors.

Thanks for your your reply grumble. I have seen pics of this sender and they seem to have two wires coming out of the tank neck but I cant work out what they are or what they are connected too. The guage is an early round VDO.

A tank sender is just a variable resistor. As yours has 2 wires then one goes to ground and the other to the gauge.

You can test the sender away from the tank before pop it in there once you have it working.