As far as I know the 3rz engines came with an oil pressure light (I don't know if the oil pressure gauge was as option or not). Mine at least, came with the switch light. I also had the cheap cluster in my truck so I swapped it to a SR5 Cluster. Until I buy a sender unit, I have just moved the wire in the gauge cluster A connector from pin location 3 (oil pressure) to pin location 4 (back door). I did this so that I wouldn't inadvertently fry my gauge, and since I don't have a back door, the light was available. Also if the back door light is on, I know I have low oil pressure, instead of just unplugging the wire from the switch light on the block. Obviously I'll change it back once I get the oil pressure sender unit so that the gauge works properly.
