Speedometer question?

[Craftsmen]

I ended up pulling the tranny out, changing the drive gear to an 8 tooth (orange/tan color ). What a bear by the way on the Saginaw. I got a big education on the inner workings of a manual transmission. I ended up running a 20 tooth (blue gear) for the driven.

With the 20 driven tooth gear according to my gps, the speedometer reads about 2 mph slow at lower speeds but a 65mph the speedo is dead on.

I did try a 19 tooth (white gear) driven gear and at lower speeds the speedo reads accurate but at 50 mph plus it about 5 mph fast on the speedo.

I went back to the 20 tooth driven, I thought it was the best compromise. Now at least my speedometer and odometer is accurate to keep me from getting tickets and to keep accurate mileage for oil changes. A big improvement from what I started with.

Saginaw 3 speed, 3:73 rear end gears, 275/60/15 rear tires.

Just a note, if you pull the bullet with the driven gear out of the tyranny it's best to jack the truck up as high as you can at the rear, this will keep the oil in your tranny. RICK