You can swap out the whole main harness but most of the needed wires are already there , just the termination is different , as above not hard to make everything connect , you usually have to extend a few of the wires to reach & the missing wire is the Tach signal wire that goes to the negative coil terminal , the oil pressure sender needs to be swapped from the light switch to the gauge sender unit but the same wire can be used but the light socket needs to be removed from the dash end of the wire .