Originally Posted by DonT
I think you will find it will make very little if any difference in fuel mileage. I doubt it will ever pay for itself in fuel savings. If you were to install a real front locker it would make a difference in the lifetime of the front end but with an open differential it won't matter.
With the current setup you cannot put a full time locker in the front end, or even a limited slip. You would not be able to turn. The guys on the Cummins forum are reporting 1-2 mpg and I figure the difference in torque between gas and diesel should make even a more profound difference.
Even with an open differential you are turning everything all the time when in 2 wheel drive. Just try turning the drive shaft with the truck on the ground. This is why older trucks used lock outs.
Another big advantage is the fact you get rid of the junk unitized wheel bearings. I had mine on my last truck go out at 80,000 miles and left me stranded on the side of the road waiting on a tow truck. The started making noise 20 miles before they went out and I was still 25 miles from home when they failed.
Figure I can repack and check my bearings every 30,000 mile when I am changing spark plugs and not have worry about the front wheel falling off.
Also it will allow the u-joints in the front axle to last a lot longer as they will not have to turn while the trucks turning. I am going to replace the current u-joints with serviceable ones while I am at it also.