1967 , 4spd Muncie, with 12 bolt 3.73 gears and with P275/60R15 tire (28").
Which speedo gear will give me the correct reading??

Thanks, Jim

I come up with a 24 assuming the drive gear in the tailhousing is an 9 tooth. An 8 tooth drive gear would use a 21.

I am not sure if it is 8 or 9? It is a steel gear not a plastic colored gear. Do you count the teeth across the wide of the gear? Or do you count how many teeth are on th edge?

There is a realy good thing on bowtie overdrives web site to figure out what gears you need. It is for automatics but a turbo 350 is 1 to 1 like the muncie so I would think it would still work. It is really nice to help you figure out what rearend gears and tires would give you.

Your friendly neighborhood GM parts person can give you a printout with all the info you are looking for including GM part #'s. The gears are usually $3-5
each as opposed to the parts catalog's price of around $10.

I went with a 21 tooth gear, seems close. But reads a little slower but 22 goes the other way.

I went with a 21 tooth gear, seems close. But reads a little slower but 22 goes the other way.

You get a 2% error with that gear. You can switch to a 7 tooth circle gear and a different driven gear and reduce the error to 1% but that is a lot of trouble.

http://chevelleengineer.home.comcast.net/speedo.htm