49 3600
I was lucky enough to find a 4.10 differential to replace my original 4.57 gear set. So, I've been having to rely on a GPS to avoid speeding tickets. I'd like to swap the original #3689178 speedometer gears in my SM420 with #3689223 gears from a 1/2 ton. That should get me close enough on the final drive ratio to ditch the GPS.
My question is (and yes, probably a stupid one) can I just pop out the original 13 tooth driven gear an pop in the 12 tooth gear or do I need to swap the drive gear too. I ask because the drive gears in both sets have 4 teeth.
Thanks in advance,
Steve
