[Yooper truck]

Thanks for the feedback..... Sorry to beat a dead horse, but I am still puzzled.

I understand there can be a difference in drive ratios to the transmission to accommodate rear gears and tire sizes. I also understand that adjustments can be made using a different speedometer gear where the speedometer cable joins the transmission. However, I did not change the speedometer gear and I am getting a different speed reading now.

So that leaves me wondering if the actual speedometer unit is calibrated different? (however looking at new speedometers from vendors there appears to be only one gauge option)

I am thinking if GM can calibrate the speedometer using a speedometer gear at the transmission, why would they need a speedometer unit that is calibrated differently at the gauge? Logically it makes no sense.

If they did not calibrate the gauges differently, then why am I getting a 5 mph difference when I changed the gauge but did not change the speedometer gear?

I'm just trying to figure this out before I throw money at something that may not be the issue.