I suppose I could wait until tomorrow or Monday (that's when I get my truck!!) to find out but I can't wait! I know I'm not supposed to engage 4Hi over 25 MPH, but how fast can I go with it engaged.

And, I assume I have to be at a stand-still to engage 4Lo if I want to keep the gears under the truck, correct?

 

4-Low will not engage unless the truck is stopped and in neutral. That is the only way it would disengage, too.

I think your 25 MPH limit on 4WH is a bit low, 50 MPH is what the standard has been

 

55 is what the book says , but I have done it at 80 by accident in the summer. I would stick with 50 or 55 in the winter, But I pull snowmobile trailers 80 in 4by for 400 or 500 miles at a time. no problem. Book doesn't say a top speed for 4by so I assume it's a 106 , thats how fast my truck goes.......