[irax]

yeah, you are going to need to put in a 1 wire 240sx coolant temp sensor some where for the water temp to work. which means you are going to need that plug off your harness as well.
for the tachometer to work you can either adjust the voltage impute like they do with rb swaps, or you can get a dakota digital tach signal converter.
for the speed signal you get the J30 diff and the dakota digital abs->speed signal converter
it HAS to be an abs diff with a signal on the nose cone. or the impute shaft