Gauges Conversion

We have a 1970 Chevelle Malibu and are right now in the progress to change the gauges into the SS-Style. But now we ran into some problems. We ordered the gauges, bezel and dashboard from NPD but how do we mount the gauges in. They don't come with any hardware and the customer service at NPD wasn't helpfull at all.
Can somebody help us please??!!