you can actually use any cluster (4 or 6) even the tach. however the tach has to be modified to work with the 4 if its from the 6 (i.e. add a resitor in the correct place.
as for the speedo, just take out your old on and put it in the new cluster. to do this you will have to take the needle off on the speedo and then put it back on after its in the new one. however you will need to go do some testing (driving a set distance with the cruise on and timing it. then do all the math to figure out how fast you were going and adjust the needle acordingly). if you someone posts a pick of the back of the v6 tach i can show you were to add the resistor and what size. if you you want a picture of the finished product go look at my cardomain site (striker2's ford) if you have any ?s just ask.
