I've got an 87, with 3.55's out back, and just installed a T-5z tranny whose case was from an unknown year Mustang. How can I tell whether I have a 7 or 8 tooth gear in the tranny? I need to know that to know what the correct speedo gear is, right? After the tranny was installed, the speedo bounced until ~60mph... And after I swapped my stock H for an off-road pipe after an emissions test, the speedo doesn't work at all. Perhaps the gear was wrong, and the teeth have gotten chewed off?