Originally Posted by budhayes3

That makes sense, the main difference is the passenger side axle and tube...on the 4x4, as TIM Z said, when 4x4 is selected, the r/s axle locks and the transfer case transfers power to the front diff. In 2wd, the r/s axle unlocks and the tcase no longer sends power to the front diff. Not sure if there will be any issues with having the r/s axle locked in while in 2wd, but I don't see why there would. Kinda like the manual locking hubs...you can lock them and still drive around in 2wd. To use the a 4x4 tcase you need the 4x4 front drive shaft also, as they are different lengths.

There are guys who have gone from 4wd to awd, with a setup like mine, and kept their front axle housing by locking the r/s axle by selecting 4wd, then unplugging it

Originally Posted by pdrcountryboy

so the front end will start wheel hopping? damn ! well the only other option is that if the 4x4 trucks some one said something about when you select 4x4 or 2 wheel drive "the front axel/ diff unlocks on locks" at least thats what i understood from they said.

if that be the case, could someone go about building a switch to just unlock the front Axel and run the awd t case? im just trying to weigh out the options, and get parts together and prices and such.

thanks for all the great feed back again and when i do the swap i will post pics and lots of info on any problems i may run into.

Originally Posted by 04herod

I was told by several ppl that with the nvg149 t-case if u were 2 take out ur front Shaft and drive around u would only make it a 1000 miles give or take b4 u burnt up ur t-case so I don't think make a set up that locks and unlocks the front axle and just leaving it n Awd would b a good way 2 go.

Originally Posted by GM eSI

The NVG 149 RPO NP3 is a single speed, single mode transfer case. The mode is full-time all wheel drive. It has a planetary differential gear set that splits the torque, normally 38 percent to the front wheels and 62 percent to the rear wheels.

The NVG 149 utilizes magnesium housings. Proper fasteners, brackets, and fill/drain plugs must be used to prevent galvanic corrosion. The planetary differential uses the carrier (6) as the input. The annulus gear (4) connects to the rear output shaft (5) and rear wheels. The sun gear (3) connects to the front output shaft (7) and front wheels through the chain (8) and sprockets. The viscous coupling (2) consists of a sealed housing filled with a high viscosity silicone fluid and thin steel plates alternately splined to the inner and outer drum. The inner drum is connected to the input shaft (1), and the outer drum to the sun gear (3). Whenever there is a speed difference between the front and rear wheels, the inner and outer plates of the viscous coupling spin relative to each other and the silicone fluid provides resistance. The resistance was tuned to be high enough to bias power quickly to the wheels with traction, and low enough to prevent binding in a tight turn on dry surfaces. This is the most common way the viscous coupling is activated, the shear mode. If the speed difference is high, the coupling can lock or hump. This "hump" occurs when the heat generated, expands the fluid inside the housing, changing the fluid dynamics between the plates. This results in pressure between the plates, forcing them into contact with each other, similar to a clutch pack. In the hump mode, the coupling can bias torque 100 percent to one axle, if required. Situations requiring this are extreme such as backing up a steep gravel grade or climbing over off-road obstacles. The viscous coupling is not serviceable; it must be replaced if defective. This is because each viscous coupling is calibrated for optimum vehicle performance for both the shear and hump modes. If the viscous coupling is in the "hump" mode too long, severe damage will occur.

To prevent damage to the viscous coupling, DO NOT:

• Tow with only two wheels down
• Drive without one propshaft
• Drive with a "donut" spare tire for an extended period of time
• Operate the vehicle on a hoist to diagnose the driveline components

Originally Posted by budhayes3

The selectable AutoTrak transfer case will swap right in, but you'll also need the front driveshaft, front diff housing (different r/s internal axle shaft since it engages and disengages as opposed to being a one piece that the AWD's have), switch, encoder motor, and 4wd computer to make it work. My truck has exactly what you're looking for, and actually I want your set up as I want to make mine full time AWD instead of selectable 4x4 (also has auto 4x4). Would you consider swapping your t-case/front drivetrain with somebody? My t-case is in perfect condition as I opened it up and inspected it last summer when I did my trans swap. I also installed the updated pump clip that's necessary to prevent the original clip from breaking and allowing the pump to rock around and wear a hole through the case, which is made of magnesium)

Shoot me up with a PM if you're interested