Please rea what i wright, i sayd that my mk.4 has alot of mk.3 parts in it, cant you read!? And NO it wont know anything if your car is a 86 or 87 and you put in a 88 - 90 instrument in it, you have to take out both the petrol gauge and the heat gauge and swap place. That you would have known if the car you have swapped it in where on of the very first mk.4 and wanted to fit the instrument from a 88-90 mk.4. By the way, are you saying that they also looks completly the same? couse then you are in for a big suprise, they dont! Its not much that differs the two but they are different!