I can only think of three possibilities. The VSS, PCM or speedo cluster. Scanning would narrow it down to 1 or 2.

i still am wondering, if my speedo is reading too fast, then is my odometer racking up more miles than i am accually driving, because it sounds like it should, but me and insane lss set our trip odometers and went for a drive but afterwords our odometers were identicle at 17.2 miles

the speedo gets a pluse from the PCM, however it then translates it to a mechanical gauge.

The VSS is located within the trans and expects the vehicle speed to be based upon predetermined gear ratio etc.

I'm not sure on this..but the VSS maybe got changed to the wrong ratio? The tires are the wrong size outter diameter?

No difference between ratios.

The PCM counts the number of pulses in a given amount of time, and applies the 'ratio' digitally within the PCM.