Ahh i see thancks for the info!.

 

As what was said before, its not advisable to run 4 HI on dry roads. It will shorten driveline parts lifespan. Transfer case is the big one. Also it wills crew your mileage up ALOT. When I had my Sonoma 4X4 even in 6" of snow I rarely used it. Had 3 70lb sand bags tied to the front of the bed and it gave me very good traction.

 

4high shouldn't do much to fuel mileage, the hubs don't disconnect at all so everything is always spinning anyway all the way up to the transfer case. It's somewhat annoying thinking that there's a mile or two per gallon being robbed, but the price of new wheels and manual hub conversion just isn't worth it.

 

My sonoma went from 20-22mph in 2wd to 12-14 in 4wd. Its just alot of uneccessary wear.

 

Did your sonoma have vacuum actuated hubs? Or an axle disconnect?

The front driveshaft, differential, both front halfshafts, and everything else are already spinning in the Dakota, so there isn't any more wear having it in 4wd aside from the fact that the t-case is in gear and it's hard on it to go around corners. It's one of the reasons you get 15-18mpg on the highway in 2wd. I have averaged 12mpg since I bought the truck, granted most of my driving is in-town and I've got something of a heavy foot.