Oil pressure sender (big one) should be right above and next to the oil filter on the passenger side of the 4.0L. The small one looks to me like the temp sender, which is on the driver's side back corner of the block just below the edge of the valve cover and under your FI stuff.
I had a messed up temp gauge, and found the Jeep has 3 temp sensors. One for the coolant temp in the thermostat housing, this sends coolant temp to the computer and has a 2-pin connector plug. One for the intake air temperature screwed into the top of the intake manifold (obviously,) this also has a 2-pin connector plug. And one (the temp sending unit) to send the motor's temp to the gauge, this has just a single post connector.
My gauge problem turned out to be just a loose wire on the sending unit.