Speedo Gear
 

After installing a Turbo 350 trans in my '65 C10 my speedometer displays a speed of about 10-15mph more than I am actually traveling. I purchased a set of several different driven gears but was wondering if anyone knows which one would be my best bet for correcting the speedo. My truck has a 373 rear end and 29" rear tires. I can probably figure it out with trying each one but thought it might be quicker with some prior knowledge.

Re: Speedo Gear
 

Do you know what the teeth are in the transmission? You can do a calculation on the TCI website - https://www.tciauto.com/speedometer-gear-calculator#350
Or an easy one - https://www.inchcalculator.com/icwid...E1NzA5ODQ3NTU=
There is a vid on how to change the gears - https://youtu.be/S6yGNIzCR04