I have a set of mechanical stewart warner gauges, and a set of electrical gauges. The mechanical ones, ie. speed uses standard speedometer cable; temperature has a hard line with a special bulb that goes into the intake,
oil pressure uses a line from the block;
oil temp has a bulb with hard line; tach and amp are electrical.
On the electrial set, they connect to sending units for fuel,
oil pressure and temperature. The sending units need to match the ohms needed for the stewart warner guages. If you already have sending units they may or may not work. I would hook them up on a bench first and see using known tempertures in a pan of water. If they are not the right ones, you will need to get sending units that match the stewart warner gauges for ohms. Hope this helps, Jim