Atlas Transfer Case, 4-Speed, 66-77 Bronco (Built To Order)

Item #: 8499NET

The Advance Adapters Atlas gear-driven transfer cases are the ultimate in gearing and strength. The customized 4-Speed Atlas Transfer Case is fully assembled and ready to install.

Atlas Transfer Case is built to order. Price reflects in cart once options have been selected. Current ETA provided after the order is placed.

Price varies based on your selections at time of order. There are many options which will affect the final price. All Atlas orders and selections will be confirmed over the phone, so please provide a good phone number when you place an order.

Fits 66-77 Ford Bronco


* Gear Ratio


* Input Spline

* Tailhousing

* Rear Yoke

* Front Yoke

* Speedometer Module

* Shifter Kit

* Site Tube

* Speedometer Connections
To make your speedometer work,
you will need one of these kits.

Atlas Transfer Case, 4-Speed, 66-77 Bronco (Built To Order)
Item #: 8499NET

California Residents: Proposition 65 Warning


Advance Adapters has built upon the proven design of the Atlas 2, to create the revolutionary Atlas 4-speed. No other transfer case on the market today has 3 separate low range ratios built into a single unit. This transfer case was designed for the off road enthusiast that likes to tackle a large variety of terrain with one vehicle. Selecting one low range ratio that works well for mud, sand and rock crawling, is a compromise but the Atlas 4-speed overcomes this limitation. One transfer case that is perfectly suited to any terrain that you may want to conquer.

The 4-SPEED has essentially two parts. The first is the reduction housing. This housing holds a planetary assembly that has a gear ratio of 2.72:1 when in "low" range, and a 1:1 in "high" range. It has one shifter coming out of the top to select the desired range. The planetary is not a synchronized shift-on-the-fly design and must be operated when the vehicle is stopped. (The main case still retains the shift-on-the-fly capability just like the standard Atlas). The reduction housing shifter is designed for a cable shifter.

The second part of the 4-SPEED may look the same as the standard Atlas, but it does have some differences. The main case of the 4-SPEED is the same raw casting, but has some machining variations to make it into a 4-SPEED. The main case functions independently from the front reduction housing and retains all of the normal Atlas features (front and rear outputs controlled independently, and the "front only" option). All of the gears are the same. The front output uses all of the same parts along with the cluster.

The strength of this unit is not an issue. We use a planetary assembly that was originally run in a NP241-HD transfer case. The six planetary gear setup has proven its durability and has been used in countless heavy-duty vehicles. Other attributes to the planetary assembly include a very quiet operation, easy shifting, and low rolling resistance. When all of this is put in front of a legendary Atlas Transfer Case, you get the best combination of gear ratios and reliability.

The 4-SPEED units will fit nearly all applications that the standard Atlas will bolt to. These will include spline counts of 21, 23, 27, 29, 31, 32 and 34. The unit has a circular bolt pattern on the front, identical to the one found in Jeep, Ford & Dodge vehicles. We have a variety of different adapters available to retrofit the 4-SPEED into nearly any application. The twin sticks for the main unit can be either the standard linkage or the cable linkage. The standard linkage is offered in a variety of custom packages available for particular vehicles and can be modified to fit many custom applications. The installation of an Atlas 4 speed should be nearly the same as the standard Atlas 2 speed. The Atlas 4 speed is just a bit longer.

We do not recommend flat towing vehicles equipped with the 4-speed due to the additional bearings used in the planetary housing.

The Atlas 4-Speed is a fully assembled "ready to install" transfer case. The Atlas is about 2 1/2" longer than your left hand drop 66-77 Ford Bronco Dana 20 so the rear driveline will have to be shortened. The front driveline may need to be lengthened. You may want to consider a body lift to make your install easier but you can install the Atlas without one (very tight fit). There are many options and upgrades for the Atlas 4. Feel free to call with any questions.

The Atlas will work with Bronco C-4s or transmissions that have been adapted using an Advanced Adapters adapter which has a separate bearing housing that holds the transfer case input shaft bearing and seal. These include C-4, C-6*, AOD, NP 435, T-18, NV 3550, and NV 4500.

The Atlas will not bolt up to a Bronco 3 speed adapter or a 3 speed adapter that has been converted to be used with an NP 435. If you have an NP 435 with a converted 3 speed adapter, call for information on how to do this conversion.

Digital Dash
If you are using a digital dash that we sell, we have an adapter kit to make these components compatible.

Speedometer Connections
Want to run the Atlas with factory Ford EFI and you can't figure out how your speed sensor is going to work? No problem, the Wild Horses Extreme team has what you need. Just select the Stock Speedometer (with EFI) Connection Kit which includes a pulse sensor, coupler, drive pin and speedometer cable.

The Stock Speedometer (No EFI) Kit is a speedometer cable that will connect your stock speedometer directly to the Atlas Transfer Case.

The Digital Speedometer Connection Kit is a speedometer cable with a coupler and drive pin for your VSS/pulse sensor which you should already have as part of your digital speedometer.

Shifter Kit
The Atlas includes a twin stick shifter for 66-77 Broncos. A cable actuated twin shifter is also available as an optional upgrade.

*Important Note: If you had to cut your C6 output shaft to use with a new Dana 20 t-case input shaft, this conversion will not work with the Atlas 4.

*Important Note: Shipping has to be calculated separately for Atlas orders. Shipping will be confirmed and approved by you before we charge your card. Please make sure to give us a good daytime phone number.