Would anybody happen to know the shift point differences btw 3.08 and 3.73 gears in a 5.3?

Also,if swapping a 3.08 to 3.73's how far off would the speedometer be??

 

Your rpm shift points would not change. I assume your gears are stock and that is why I am going to say your truck does not have 3.08 gears. Most likely you have some 3.42's. Check your rmp's when you are at 55mph and in overdrive. If your tach read 1500rpm, you have 3.42's. If it reads in the 1630's you have 3.73's.
Provided you do have 3.08 gears in your truck and went with 3.73's, your speedo would be off by 21.1%.

 

I know that I have 3.73's, I'm just asking it theoretically.And I was wondering shift point diff.in MPH

 

with the 3.08's you would have less shift extension so the rpms would drop more on the shifts (that is not your question I know).

I went from 3.08's to 3.73's in my Tahoe and my gas mileage went down but the truck is much stronger from a dig and from a roll.

 

I was under the impresion rpm shift points can only be changed by computer tuning and not by changing the rear end gear ratio. Going from 3.08 to 3.73 would have his truck shifting at lower mph so his mph shifting points would change. Would someone please correct me if I am wrong.