Oil pressure wiring to 90 Suburban gauges

[Tilt]

I'm trying to figure out the wiring for swapping the 90 Suburban gauge cluster into my 86. My truck originaly had the idiot lights. I found the pin outs and have swaped the wires swapped around. What I'm having questions about is the oil pressure gauge. I got a new harness form BP Automotive which does not have the conneter for the oil sending unit. If I get the connector for it from the original harness, will one of the wires have the correct reading that I can run to the pin location on the gauge cluster harness and have the gauge read correctly? If not, what is the best route to take to get the Suburban gauge working?