I've got a question about the right speedo driven gear for a new rear axle setup I've got. I have a 700R4 auto trans, 245/50/16 tires, and went from a 2.73 to 3.42 rear axle. Do I need a 44 tooth driven gear or a 45 tooth? TIA

You can use either one to leave your speedo inaccurate.

If you want it accurate, replace the 17 drive gear with a 15 and use a 42 driven.

You can use either one to leave your speedo inaccurate.

If you want it accurate, replace the 17 drive gear with a 15 and use a 42 driven.

This is why we have the stickies.
https://www.thirdgen.org/forums/tran...eedometer.html

Why do I need to replace the drive gear? I did look at the sticky and did the math. I came up with a 45 driven gear. Also, the website below also had a chart saying I need a 45 driven gear with a 17 tooth drive gear.

http://www.transmissioncenter.net/sp...f2bhoCI8zw_wcB

Read this post: https://www.thirdgen.org/forums/tran...ml#post5294515

and this thread:
https://www.thirdgen.org/forums/tran...ter-gears.html

And then do whatever your heart desires.

The post with that chart you posted with tire sizes and gear ratios was very helpful. I couldn't find that chart in my shop manual. Thank you.