I put 4.10's in and all I can find is a 23 tooth that works for the 3.55's for an automatic. It seems like I need a 25 or 26 tooth gear but no one makes it. Anybody seen one?
No one makes one - you'll need to change the drive gear in the tranny as well in order to make the ratios work out. Here's a site that may help with info.
Stewart-Warner makes a speedo gearbox adapter that fits between the trans and the speedo cable. They have a quick change gearset inside that allows you you use a combination of gears to correct the speedo reading. The speedo gearbox adapter is very popular with big trucks, since they change tire sizes often and need accurate speedometers. Check the Yellow Pages to see if there is a Speedomter shop in your area. See http://www.stewartwarner.com/ to find a distributor in your area.