What year Cobra btw ?
Could be a couple of different reasons why. Maybe both factory dash gauges went south.
Or, it's more likely that the previous owner unplugged the factory sending units for the oil pressure and water temperature dash/cluster gauges and used those locations for the corresponding aftermarket/Autometer sending units to get a signal for the A-pillar gauges.
RE the factory oil pressure sending unit location:
If you look underneath the car, by the oil filter, you *might* see an unplugged black 2 or 3 wire electronic harness that "plugs" into a threaded port that goes into the oil filter housing/elbow. If this harness is unplugged, simply plug it back in.
Or, if the port on the oil filter housing is sealed up with a blank hex/allen plug, you will have to remove that and find the correct "plug" harness that seats into this position in order to connect the wired sending unit portion into this plug.
*note* Sometimes the factory oil pressure sending unit on Cobras fail and a new sending unit from Ford has to be installed (Ford updated the oil psi part number at one point; possibly a newer/revised part). So it is also possible that the factory sending unit is STILL hooked up, but it has failed and a new one should cure it ($12 or so for the part IIRC).
RE factory water temperature gauges - IIRC, the 96-98s should have a couple of different locations near the coolant crossover tube (black tubing by alternator at front of engine); think one spot is for the PCM and the other is for the dash gauge. Don't quote me on that though...can't recall for 99+ at the moment.