Does anyone out there know if I need to change anything else besides the ring and pinion if I upgrade from 3.55 to 4.56 on my rear differential?

 

By the way this is on an 89 F150 with an 8.8 differential

 

speedo will need to be fixed. If you buy the ring and pinion kit it should come with all you need to swap out the ring and pinion.
Have reputable shop do the install, gears are either perfect or needs to be taken back and done over.