I am 99% done with my 95 camaro dash install and I know a lot of people have been wondering if a SGI 5 box will be needed. Well, I have a T56 and I do need the box still. The grn/wht wire on the 4th gen cluster splices into the grey wire on the drivers side 3rd gen connector. It is the top grey wire on the inside. My speedo works while I drive but it reads about 80mph when I come to a stop or when the car is idling. I had this problem with my old dash too. Not sure why it does this. If the grey wire is not connected to anything, you will get a code 24 for the VSS.