My car is equipped with a TH400 tranny and I just replaced my rear end which was originally a 10-bolt 3.55:1 limited slip with a 12 bolt 3.73:1 posi. Of course my speedometer is now out of whack, so does anyone know specifically how I can at least get it close to what it was before? I have a TH400 tranny. (I didn't change the tires or anything else.) Thanks Gary
Take the gear out of the tranny, and count the teeth. Go to your local dealer and get a gear that has one or two less teeth. This will get you close. The 75 and older parts book has a chart for speedo gears, but with the advent of computer parts programming, your dealer might not have this catalog.