I just finished installing a new transmission and now the speedometer is off a bit. I didn't change my original gear, It is all original - speedo says 50 actual it's somewhere between 41-43 mph. I have a 93 and the trans is supposedly out of a 98 mark viii. Any suggestions on what I need to get it right? Obviously a new speedo gear but I don't know which one but I currently have a green gear.