I know the manual says that you shouldn't go above 55MPH in 4HI. I think it also says don't use 4HI or LO on dry pavement. Well...yesterday when I turned off the dirt road, I forgot that I was still in 4HI. I was doing 75+ on dry pavement and only noticed the 4X4 light on about three miles later. Could I have possibly damaged something by doing this? I used 4HI again today and it felt alright.

 

I believe the manual states not to switch to or from 4hi above 55. There is no reason why you can't go faster than 55 while in 4hi. As far as damage, I doubt you did any in that short time, especially if there were no sharp turns that would have bound up the front. This also would have clued you that it was in 4hi.
The reason not to go into or out of 4hi above 55 is the componets would go from 0-55 or 55-0 instantly.

 

I remember a thread from awhile ago similiar to this one. One guy I work with drives with his truck in 4x4 all winter long, and has been known to drive at speeds of 180 kph. Nothing ever goes wrong with his truck either.

 

some times i drive in 4x4 at lights and such when its raining. My mud tires realy dont like to stick on wet roads so i have to have it in 4x4 to stop my backend from slideing out.