Before you flame this Jeeper I did a search 4 diffrent ways.
I'm asking this for a friend at work.
He has 1986 K5 Blazer 305, with 410 gears and 33"tires
He is looking to replace the speedo gear but I cant find a chart for Blazers.
Anyone got a link to one.

If you can find one for the pickups. it will be the same.

This is my Blazer. I had afriend from work post for me. I have switched from 3.08 to 4.10 for towing our camper. My speedo is now off 10-15 mph. Didn't know if anyone knew what color speedo gear I needed from past experience.

You can maybe scrap one from a truck that came with 4.10s stock if you hav'nt changed tire size. Maybe even order one from dealer or somebody. Easiest thing would be to ask a tranny shop though. By the way speedometers are off by a percent, yours should be about 24% off but my math aint to good right now.


Charlo

Your math seems about right. I think I may have found my solution. TCI transmission's web site has a calculator just for this. Now it is just a matter of me pulling out my current speedo gear from the x-fer case and counting the teethe on my drive gear. The 700R4 only came with 5 different drive gears 15, 17, 18, 19, and 20 tooth. Once I figure out which one I have, I input that, my gear ratio and tire size into their calculator and it will give the driven gear tooth count I need. All I have to do is go and buy the closest one from GM.

Thanks to those who offered to help. Maybe this can also help anyone else who is having this problem.

The 700R4 only came with 5 different drive gears 15, 17, 18, 19, and 20 tooth
If your tooth count comes out as something not offered stock you may still be able to get an aftermarket one from a tranny shop or something. Shit you might even be able to make one.


Charlo