I cant find the info in the owners manual or on this site. I know I have seen it somewhere. What is the max recommended speed while in 4wd Hi? As in hard packed snow on the hiway (other than good common sense)

04 F250 V10 3.73 Auto

 

i am pretty sure you can drive as fast as you want. when ever people run there trucks at the drag strip they run them in 4 hi and run up to aroud 100mph

 

There really isn't any problem running high speeds in four high, as long as the front drive shaft is well balanced there is really no differnce, there would be a little more heat in the transfer case, but as long as it was slick out you would be ok, I wouldn't be afraid to run any speed in four high, but usilly if I can drive 50mph+ I am in 2wd anyways.

 

If the road is slick enough for four wheel drive, you can drive way faster in 4x4 than you will want to go.