speedometer questions

[Coveted]

okay so i switched my 2.29 non posi rear end for a 3.73 posi rear end.
I'm only running the stock speedo for the summer, and I'm not going to remember to add or subtract MPH everytime I look at the speedo.

So Im wondering how do I make it accurate?

 

[dan2286]

http://www.transmissioncenter.net/speedometer_calibration_______va.htm

You have to change the speedo gear. The formula is on this site.[/u]

 

[Coveted]

nice I didn't see anything for the powerglide, But I found a local speedo place around me, So I'll be giving them a call 😀