Butch
I'm awesomeR!
Can you shift into four wheel high while driving? I have always stopped but my girlfriend reached down and yanked it into four wheel high going about 35mph. It was fine but since I dont feel like replacing anything right now I figured i'd ask the experts.
You can but I prefer to be stopped and if you do it, it shouldn't be any faster than 25mph IMO I've done it with both push button (NP243/non autotrac) and floor shifted (NP241) many times out of necessity with only having to replace the rear seal on the NP243 but keep in mind your meshing moving parts that would fair better from lower speeds or non at all.