Before you order anything... make sure you have someplace that can make custom driveshafts. You'll likely need one.
There are units that bolt to the trans much like a tranfer case.
I don't know if anyone makes a 2 speed axle for vehicles that size.
Your other option, and maybe cheaper, is see if there is an OD trans you can put in. Tho if it has an electronic trans that isn't allot of fun either.
If you do have an electronic trans... that can complicate the use of bolt on or axle od units as well. The PCM can get confused by the extra gears and trip error codes because it thinks the trans or the TC clutch is slipping. Some manual tans vehicles can react the same way now. It depends what year the truck is so make sure that any unit you look at has an answer for such an issue.
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
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