I'm having 3.42's put into my rear end. The car had 2.73's in it and was wondering if any knew what speedo gears I needed to get my speedometer to read correctly with the new gear?

Also, I did see the sticky above with the 700R4 speedo gears. The cheat sheet someone listed doesn't have my standard P235/55R16 listed. Would I still use a 40 drive/15 driven?

 

I used the speedo gear calculator I always use on JAM Performance's website. Typed in your tire size and this is what I came up with. If you keep the red, 17 tooth drive gear in your trans, which is what the factory used with 2.73's, it calls for a 44.7 tooth driven gear, which comes to 45 tooth when you round it up. If you change your drive gear on the output shaft of the trans to the gray, 15 tooth drive gear, which is what the factory used with 3.42's, it calls for a 39.4 tooth drive gear, which rounds down to a 39 tooth driven gear. Honestly, it'd be best to install the gray, 15 tooth gear because the 39 tooth driven gear is usually easier to find than the 45 tooth gear. I've always used JAM's calculator whenever I've changed rearend gears, and it usually comes out pretty accurate. Hope this helps!