Rather than change out the gears, I used a speedo adapter available from Jim Carter. This gives the ability to calibrate your speedo with exact accuracy specific to your truck, more accuracy than a gear change. You can determine your individual
requirements using GPS...no need to send out the speedo. I am very happy with the result.
Here is the link--
http://www.oldchevytrucks.com/cart/product.asp?prodid=SP249&i=9939|||||
