Speedometer & odometer accuracy

I've changed plenty of speedometer Drive pinions to match rear ends and tire size to make the speedometer and odometer accurate. For some reason I cannot get this one too workout wonder if anybody has any ideas. I have 2.94 rear gears in tires measure 28 1/4 from the ground to the top of the tire vehicle weight sitting on the tire) approximately 28 3/4 side to side. According to the charts I need a 28 tooth Speedo gear and with this gear speedometer is 4 1/2 miles per hour off up to 50 miles per hour and 10 miles per hour off after 50 miles per hour. The odometer reads about 9/10 of a mile for every mile driven compared to the GPS.

I also have a 31 tooth gear that I originally installed when I thought it had 3.23 gears, but apparently somebody has changed the gear set over the years to the 2.94. the odometer reads 1 & 1/10 mile for every mile driven and the odometer seems about 3 miles per hour off all over.

So any ideas? how much does one tooth change the odometer and speedometer? Usually putting the gear that the chart recommends, I'm within 1 mile per hour and the odometer is pretty dang close on the rest of my Mopars. in case you couldn't guess by the tire size, this is my two wheel drive pickup not my Coronet, dart or B body van.

My experience is that a one tooth change is good for a 1 to 2 mph reading change.

Speedo worn ? My dart and coronet are very accurate

I have swapped the cluster out but I never ran the original one because the best housing is destroyed. I could probably prop it up on the dash and connect it up and see how it reads

Clock it a little differently?