Fuel pressure gauge install

I have an electric fuel pressure gauge. Where do I need to put the sending unit? I assume I just put it on the fuel rail but is there a place I can screw it in or do I have to drill and tap a hole?

I've never heard of one of those.. What did that cost?

well is just like any other gauge, the ones made by autometer are around 150, I just got a cheap one from glowshift for 50. I figured I would see if it works or not, its going in the glove box so looks dont matter but it seems to fairly nice.