i found a used gauge cluster for sale, now if i were to install it in my car will it work?? it is from the same w202 from what the guy has told me... will the mileage from my car display or is the mileage stored in the cluster? also i have seen that the SRS light will come on... is that b/c the battery was not disconnected?? well is this possible, just plug and play or should i jus forget about it, if there is more intricate electronic sh*t involved... thanks