temp & oil gauge not working

The limiter produces a pulse voltage. A digital volt meter will flash 2.XX and 3.XX. That voltage travels through the winding of each gauge and should appear at gray wire out at oil sender, purple wire at temp sender. So take a volt meter to the engine bay. If you don't find pulse voltage at the sender wires, Something is wrong upstream. Wires in wrong positions of bulkhead connector, loose attaching nuts behind the gauge, failed gauge, etc...
If you prove pulse voltage at those sender wires, you prove all upstream is working.
With switch off attach a sender wire directly to ground. At switch on the corresponding gauge needle should travel to its highest position in a smooth motion and quite rapid rate. Keep this test brief since this zero ohms path can overheat the gauge. At switch off the needle should travel all the way home about the same as it went up. Not a swiss watch slick movement but fluid like enough to satisfy. If a needle hangs, jumps, or doesn't travel the full distance in either direction... faulty gauge.
If all proves good the fault must be at senders. They do need chassis ground and too much Teflon tape on their threads might interrupt that ground path.
Wrong sender ? The oil sender meant for a oil warning lamp will not work a oil gauge.
A varying resistance through proper sender to chassis ground causes heat in the gauge that moves the needle. So next test would be run engine with sender wires disconnected ( and isolated from ground of course ) and use ohm meter to find what ohms signal the senders are making. You would have to wait for hot water before the temp sender shows something within the 80-10 ohms range. Thermostat opens at what 180? 195? That's somewhere around 35 ohms.
If you know you have oil pressure the sender should show less that 80 ohms right away. For example... approx' 14 ohms is approx' 60 psi and approx' the 'U' in PRESSURE on that gauge screen.