I just bought my '98 5.4 4x4 with 3.73's and 16 inch 255/70's.

I want to go about an inch taller. Who has programming to adjust the speedo, and will I need to change shift points also?

 

I'm not sure if you can change the speedo gear in a '98 or not. If so, you should be good. Otherwise it'd have to be done in the PCM. Best way to do it is with a Superchip. Good excuse for a chip.

 

Your speedo is going to be off by only ~3% (that’s about 2 mph at 70 mph). I hardly think it's worth the time and effort to correct such a negligible difference. Don’t worry about shift points. If you feel compelled to fix, I’m pretty sure that ’98 models have the gear inside the tranny housing affording you the ability to correct discrepancies with a relatively inexpensive fix.

 

I know on the 2000 models that the dealer can change this info on your computer by hooking up some kind of tool to it. Don't know if it will work on a 1998 but it worth asking your dealer.